Open-Source Multicolour 3D Printing Upgrade: Clem’s 3D Chameleon Remix -- Episode 693

What is the 3D Chameleon MK4, and why it matters

The 3D Chameleon MK4 is a retrofit add-on for standard 3D printers: a multicoloured filament changer that lets you print objects in several colours using a single hotend. Instead of needing multiple extruders or a complex multi-material hotend, it physically swaps different 1.75 mm filaments via a lever-and-switch mechanism. When the printer’s tool-head moves to a fixed “actuator” spot, it mechanically presses a switch. Based on how long the switch is held, the Chameleon controller triggers filament unload/load sequences. That way you can change colour or material mid-print while staying compatible with virtually any FDM printer and often without modifying the printer’s own firmware. This design makes multicoloured printing accessible, especially for makers who prefer a simpler, retrofit solution over buying an expensive multi-extruder machine.

The MK4 version supports up to four filament channels, offering a flexible way to produce multi-colour prints while reusing a typical single-extruder setup.

But while the mechanical side was robust, the electronics and firmware were dated, and sourcing components for a new build had become harder. That’s where Clem’s work comes in.

Rebuilding from the inside: Why Clem decided to redesign

Clem chose to preserve the proven mechanical parts of the MK4, the filament paths, lever system, bearings, and spring-loaded drives, but to rebuild everything around them: the electronics, firmware, board layout and feedback mechanism. Calling the result 3D Brookesia, he aimed for a version that’s easier to source, more reliable, and simpler to assemble by hand. As he says: “We take an open source design and iterate on it… and contribute to the project while making bespoke hardware that perfectly fits your use case.”

How the original system works, and what’s kept

The core of the 3D Chameleon’s magic is its use of a single micro-switch to orchestrate filament swaps. The printer moves the head to press the switch; the controller measures how long it’s pressed to decide whether to load, unload or change filament. During that hold, the stepper motor vibrates: “one vibration per second,” Clem explains, giving a tactile “tick-tick” so you can count the pulses for correct timing. No electronics connecting into the printer’s mainboard are needed; the only requirement is that your G-code includes moves to the actuator switch and filament-change commands. This preserves compatibility with nearly any standard FDM printer.

This mechanical-switch–based approach avoids expensive multi-extruder hardware or complex firmware mods, and keeps the system portable and extendable.

What Clem changed: hardware and firmware improvements

Modern microcontroller: ATtiny3226

The original MK4 board uses an ATmega328P, like an Arduino Uno, a reliable platform years ago, but increasingly obsolete. Clem migrated all firmware to an ATtiny3226, a modern UPDI-programmable chip that’s faster, doesn’t need an external crystal, and is easier to source. That involved remapping every pin via the MegaTinyCore framework and stripping out I²C-dependent code. As Clem notes, leaving in unused I²C routines caused the original firmware to “actively search for those devices on startup,” and stall if it didn’t find them. The new build avoids that, simplifying startup and reducing points of failure.

Quieter, cooler drivers: TMC2209

To replace the older DRV8825/A4988-style drivers, Clem installs TMC2209 stepper drivers. These run cooler and with less noise. Because TMC2209 modules depend on a stable logic voltage rail to detect their reference voltage at boot, Clem adds Schottky diodes to ensure logic voltage comes up before motor power, preventing issues such as mistaken UART mode or mis-detection. As Clem puts it: “This makes sure that the chip can automatically detect its voltage reference level and then goes into read mode.”

Thermistor-monitored cooling

Stepper drivers and an enclosed chassis can build up heat, so Clem adds a thermistor circuit feeding a PWM-controlled fan. The thermistor forms a voltage divider connected to an analog pin; firmware reads its resistance (using the Beta curve) and, if temperature exceeds the threshold (30 °C in initial tests), triggers the fan via a MOSFET. During testing he observes: “If I touch the NTC… the fan will engage.” He also corrected a MOSFET pin orientation issue caused by a footprint error — a small but important fix.

Visual feedback via LEDs

One drawback of the original MK4 is lack of clear feedback about which filament channel is active. Clem solves this by adding a row of LEDs mounted along the enclosure. Instead of manually writing LED-toggle code all over the firmware, he implements a small helper function.

That means whenever the original firmware would display a status message (e.g. on a small screen or serial console), the remixed version now lights up the corresponding number of LEDs. As Clem asks: “Do you remember still on which extruder this thing now is?” The LEDs give immediate, visible feedback.

PCB layout for hand-assembly

To make the project accessible for DIYers, Clem redesigned the board layout. He replaced proprietary connectors with standard screw-terminals or headers, placed all connectors along board edges for easy access, and sized the board to slide into a standard Hammond 1455 aluminium enclosure. He even added custom 3D-printed end plates for tidy cable routing and airflow. As he says: “My version is made so you at home can assemble it yourself with just a soldering iron.”

Mechanical side remains unchanged, and why that matters

Because the mechanical changer works reliably, Clem decided not to alter it. The lever system, springs and bearings remain exactly as in the original MK4 design. That means all prior knowledge, print profiles and G-code workflows remain valid. The community still sources the same springs and bearings, though Clem cautions that obtaining some parts may be slightly harder in Europe than in the US. With some patience, builders can still assemble a fully functioning mechanical changer that swaps up to four filaments in sequence.

Maintaining compatibility with original workflows

Clem reviewed the original MK4’s firmware and schematics from its GitHub repository to map every function. His process followed a “reproduce first, then improve” path: replicate all behaviours, switch monitoring, timed presses, stepper control, filament load/unload, vibration feedback, and then add enhancements. The updated firmware retains the core logic unchanged, ensuring the device still responds to the same press-patterns and G-code triggers but gains better reliability, thermal control, and clearer user feedback.

Because the integration happens entirely outside the printer (via G-code moves and a switch), no changes are needed on the printer side. This keeps the upgrade simple, low-cost, and broadly compatible.

Using the new system

The hardware runs on 12 V, either from a separate power supply or the printer’s PSU. Clem estimates that ~1.5 A is enough for the system. “1.5 amps is plenty enough to run this,” he says.
The printer’s print job flow doesn’t change. The slicer or pre-processor inserts standard G-code moves so the print-head hits the actuator switch at the right time. The firmware selects the correct filament channel (based on how long the button was pressed) and runs the load/unload sequence.
During testing, switching colours and loading filament worked exactly like the original – but with added benefits: quieter drivers, active cooling, and instant visible feedback via LEDs.

Why this redesign matters

The 3D Chameleon MK4 delivers a clever, low-cost method to get multi-color prints without buying a full multi-extruder system. But over time, some of its electronics and components have become hard to source or outdated. Clem’s 3D Brookesia redesign addresses those issues: it updates the internals with modern, available parts, removes unnecessary complexity, and adds user-friendly upgrades, all without touching the mechanical side.

In doing so, the project reaffirms what open-source hardware can deliver: community-driven evolution, improved DIY experience, and extended longevity for creative tools.

Supporting Files and Links

- Github Repo for 3d Chameleon MK4 original version

Bill of Materials

Product Name	Manufacturer	Quantity	Buy Kit
3D Printer Filament, PETG, Black, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Orange, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Blue, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, White, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
Microswitch, M140T01 Series, SPDT, Roller Lever, Solder, 5 A, 250 V RoHS Compliant: Yes	Multicomp pro	1	Buy Now
ATTINY3226-SU	Microchip	1	Buy Now
STEPPER MOTOR, 1.8DEG, 5MM, BIPOLAR ROHS COMPLIANT: YES	DFROBOT	2	Buy Now
Power MOSFET, N Channel, 55 V, 47 A, 0.022 ohm, TO-220AB, Through Hole	Infineon	1	Buy Now
NTC THERMISTOR, 10KOHM, AXIAL LEADED ROHS COMPLIANT: YES	EATON	1	Buy Now
Evaluation Board, TMC2209 SilentStepStick, 2-Phase Motor Driver	Trinamic	2	Buy Now
1455N1201BU	Hammond	1	Buy Now

Additional Parts

Product Name
Springs
Screws
Bearigns according to original 3D chameleon MK4 BOM

Tags: filament changer, diy 3d printer upgrade, multicolour 3d printing, multicolour extrusion, 3d printer mod, tmc2209 drivers, attiny3226, multicolour fdm printing, gcode filament change, pcb redesign, firmware porting, thermistor cooling, 3d chameleon, friday_release, open source hardware, stepper driver upgrade

Open-Source Multicolour 3D Printing Upgrade: Clem’s 3D Chameleon Remix -- Episode 693

cstanton — Thu, 04 Dec 2025 12:59:30 GMT

Revision 10 posted to Documents by cstanton on 12/4/2025 12:59:30 PM

Watch the Project Build

What is the 3D Chameleon MK4, and why it matters

The MK4 version supports up to four filament channels, offering a flexible way to produce multi-colour prints while reusing a typical single-extruder setup.

But while the mechanical side was robust, the electronics and firmware were dated, and sourcing components for a new build had become harder. That’s where Clem’s work comes in.

Rebuilding from the inside: Why Clem decided to redesign

How the original system works, and what’s kept

This mechanical-switch–based approach avoids expensive multi-extruder hardware or complex firmware mods, and keeps the system portable and extendable.

What Clem changed: hardware and firmware improvements

Modern microcontroller: ATtiny3226

Quieter, cooler drivers: TMC2209

Thermistor-monitored cooling

Visual feedback via LEDs

PCB layout for hand-assembly

Mechanical side remains unchanged, and why that matters

Maintaining compatibility with original workflows

Using the new system

The hardware runs on 12 V, either from a separate power supply or the printer’s PSU. Clem estimates that ~1.5 A is enough for the system. “1.5 amps is plenty enough to run this,” he says.
The printer’s print job flow doesn’t change. The slicer or pre-processor inserts standard G-code moves so the print-head hits the actuator switch at the right time. The firmware selects the correct filament channel (based on how long the button was pressed) and runs the load/unload sequence.
During testing, switching colours and loading filament worked exactly like the original – but with added benefits: quieter drivers, active cooling, and instant visible feedback via LEDs.

Why this redesign matters

In doing so, the project reaffirms what open-source hardware can deliver: community-driven evolution, improved DIY experience, and extended longevity for creative tools.

Supporting Files and Links

- Github Repo for 3d Chameleon MK4 original version

Bill of Materials

Product Name	Manufacturer	Quantity	Buy Kit
3D Printer Filament, PETG, Black, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Orange, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Blue, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, White, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
Microswitch, M140T01 Series, SPDT, Roller Lever, Solder, 5 A, 250 V RoHS Compliant: Yes	Multicomp pro	1	Buy Now
ATTINY3226-SU	Microchip	1	Buy Now
STEPPER MOTOR, 1.8DEG, 5MM, BIPOLAR ROHS COMPLIANT: YES	DFROBOT	2	Buy Now
Power MOSFET, N Channel, 55 V, 47 A, 0.022 ohm, TO-220AB, Through Hole	Infineon	1	Buy Now
NTC THERMISTOR, 10KOHM, AXIAL LEADED ROHS COMPLIANT: YES	EATON	1	Buy Now
Evaluation Board, TMC2209 SilentStepStick, 2-Phase Motor Driver	Trinamic	2	Buy Now
1455N1201BU	Hammond	1	Buy Now

Additional Parts

Product Name	Manufacturer	Quantity
Springs
Screws
Bearigns according to original 3D chameleon MK4 BOM

2361595

Open-Source Multicolour 3D Printing Upgrade: Clem’s 3D Chameleon Remix -- Episode 693

e14sbhargav — Thu, 04 Dec 2025 12:59:30 GMT

Revision 11 posted to Documents by e14sbhargav on 12/4/2025 12:59:30 PM

Watch the Project Build

What is the 3D Chameleon MK4, and why it matters

The MK4 version supports up to four filament channels, offering a flexible way to produce multi-colour prints while reusing a typical single-extruder setup.

But while the mechanical side was robust, the electronics and firmware were dated, and sourcing components for a new build had become harder. That’s where Clem’s work comes in.

Rebuilding from the inside: Why Clem decided to redesign

How the original system works, and what’s kept

This mechanical-switch–based approach avoids expensive multi-extruder hardware or complex firmware mods, and keeps the system portable and extendable.

What Clem changed: hardware and firmware improvements

Modern microcontroller: ATtiny3226

Quieter, cooler drivers: TMC2209

Thermistor-monitored cooling

Visual feedback via LEDs

PCB layout for hand-assembly

Mechanical side remains unchanged, and why that matters

Maintaining compatibility with original workflows

Using the new system

The hardware runs on 12 V, either from a separate power supply or the printer’s PSU. Clem estimates that ~1.5 A is enough for the system. “1.5 amps is plenty enough to run this,” he says.
The printer’s print job flow doesn’t change. The slicer or pre-processor inserts standard G-code moves so the print-head hits the actuator switch at the right time. The firmware selects the correct filament channel (based on how long the button was pressed) and runs the load/unload sequence.
During testing, switching colours and loading filament worked exactly like the original – but with added benefits: quieter drivers, active cooling, and instant visible feedback via LEDs.

Why this redesign matters

In doing so, the project reaffirms what open-source hardware can deliver: community-driven evolution, improved DIY experience, and extended longevity for creative tools.

Supporting Files and Links

- Github Repo for 3d Chameleon MK4 original version

Bill of Materials

Product Name	Manufacturer	Quantity	Buy Kit
3D Printer Filament, PETG, Black, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Orange, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Blue, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, White, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
Microswitch, M140T01 Series, SPDT, Roller Lever, Solder, 5 A, 250 V RoHS Compliant: Yes	Multicomp pro	1	Buy Now
ATTINY3226-SU	Microchip	1	Buy Now
STEPPER MOTOR, 1.8DEG, 5MM, BIPOLAR ROHS COMPLIANT: YES	DFROBOT	2	Buy Now
Power MOSFET, N Channel, 55 V, 47 A, 0.022 ohm, TO-220AB, Through Hole	Infineon	1	Buy Now
NTC THERMISTOR, 10KOHM, AXIAL LEADED ROHS COMPLIANT: YES	EATON	1	Buy Now
Evaluation Board, TMC2209 SilentStepStick, 2-Phase Motor Driver	Trinamic	2	Buy Now
1455N1201BU	Hammond	1	Buy Now

Additional Parts

Product Name	Manufacturer	Quantity
Springs
Screws
Bearigns according to original 3D chameleon MK4 BOM

2361595

Open-Source Multicolor 3D Printing Upgrade: Clem’s 3D Chameleon Remix -- Episode 693

cstanton — Thu, 04 Dec 2025 12:54:39 GMT

Revision 9 posted to Documents by cstanton on 12/4/2025 12:54:39 PM

Watch the Project Build

What is the 3D Chameleon MK4, and why it matters

The 3D Chameleon MK4 is a retrofit add-on for standard 3D printers: a multicolor filament changer that lets you print objects in several colors using a single hotend. Instead of needing multiple extruders or a complex multi-material hotend, it physically swaps different 1.75 mm filaments via a lever-and-switch mechanism. When the printer’s tool-head moves to a fixed “actuator” spot, it mechanically presses a switch. Based on how long the switch is held, the Chameleon controller triggers filament unload/load sequences. That way you can change color or material mid-print while staying compatible with virtually any FDM printer and often without modifying the printer’s own firmware. This design makes multicolor printing accessible, especially for makers who prefer a simpler, retrofit solution over buying an expensive multi-extruder machine.

The MK4 version supports up to four filament channels, offering a flexible way to produce multi-color prints while reusing a typical single-extruder setup.

But while the mechanical side was robust, the electronics and firmware were dated, and sourcing components for a new build had become harder. That’s where Clem’s work comes in.

Rebuilding from the inside: Why Clem decided to redesign

Clem chose to preserve the proven mechanical parts of the MK4, the filament paths, lever system, bearings, and spring-loaded drives — but to rebuild everything around them: the electronics, firmware, board layout and feedback mechanism. Calling the result 3D Brookesia, he aimed for a version that’s easier to source, more reliable, and simpler to assemble by hand. As he says: “We take an open source design and iterate on it… and contribute to the project while making bespoke hardware that perfectly fits your use case.”

How the original system works, and what’s kept

This mechanical-switch–based approach avoids expensive multi-extruder hardware or complex firmware mods, and keeps the system portable and extendable.

What Clem changed: hardware and firmware improvements

Modern microcontroller: ATtiny3226

Quieter, cooler drivers: TMC2209

Thermistor-monitored cooling

Visual feedback via LEDs

PCB layout for hand-assembly

Mechanical side remains unchanged, and why that matters

Maintaining compatibility with original workflows

Clem reviewed the original MK4’s firmware and schematics from its GitHub repository to map every function. His process followed a “reproduce first, then improve” path: replicate all behaviors, switch monitoring, timed presses, stepper control, filament load/unload, vibration feedback, and then add enhancements. The updated firmware retains the core logic unchanged, ensuring the device still responds to the same press-patterns and G-code triggers but gains better reliability, thermal control, and clearer user feedback.

Using the new system

The hardware runs on 12 V, either from a separate power supply or the printer’s PSU. Clem estimates that ~1.5 A is enough for the system. “1.5 amps is plenty enough to run this,” he says.
The printer’s print job flow doesn’t change. The slicer or pre-processor inserts standard G-code moves so the printhead hits the actuator switch at the right time. The firmware selects the correct filament channel (based on how long the button was pressed) and runs the load/unload sequence.
During testing, switching colors and loading filament worked exactly like the original – but with added benefits: quieter drivers, active cooling, and instant visible feedback via LEDs.

Why this redesign matters

In doing so, the project reaffirms what open-source hardware can deliver: community-driven evolution, improved DIY experience, and extended longevity for creative tools.

Supporting Files and Links

- Github Repo for 3d Chameleon MK4 original version

Bill of Materials

Product Name	Manufacturer	Quantity	Buy Kit
3D Printer Filament, PETG, Black, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Orange, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Blue, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, White, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
Microswitch, M140T01 Series, SPDT, Roller Lever, Solder, 5 A, 250 V RoHS Compliant: Yes	Multicomp pro	1	Buy Now
ATTINY3226-SU	Microchip	1	Buy Now
STEPPER MOTOR, 1.8DEG, 5MM, BIPOLAR ROHS COMPLIANT: YES	DFROBOT	2	Buy Now
Power MOSFET, N Channel, 55 V, 47 A, 0.022 ohm, TO-220AB, Through Hole	Infineon	1	Buy Now
NTC THERMISTOR, 10KOHM, AXIAL LEADED ROHS COMPLIANT: YES	EATON	1	Buy Now
Evaluation Board, TMC2209 SilentStepStick, 2-Phase Motor Driver	Trinamic	2	Buy Now
1455N1201BU	Hammond	1	Buy Now

Additional Parts

Product Name	Manufacturer	Quantity
Springs
Screws
Bearigns according to original 3D chameleon MK4 BOM

2361595

Open-Source Multicolor 3D Printing Upgrade: Clem’s 3D Chameleon Remix -- Episode 693

cstanton — Thu, 04 Dec 2025 12:39:58 GMT

Revision 8 posted to Documents by cstanton on 12/4/2025 12:39:58 PM

Clem rebuilds the 3D Chameleon MK4 from the ground up, replacing the legacy electronics with a modern ATtiny3226 controller, TMC2209 drivers, thermistor-controlled cooling, and clearer status indicators. The mechanical system stays true to the original open-source design, but the updated hardware is easier to assemble, easier to source, and designed for reliable multicoloured filament changes without modifying your printer’s firmware.

Watch the Project Build

The 3D Brookesia

Clem set out to rebuild the electronics behind the 3D Chameleon MK4 so the system could be assembled with current parts, hand-soldered at home, and extended with new features. He kept the proven mechanical changer but redesigned everything around it, naming the result the 3D Brookesia after a small chameleon species. As he puts it, “We take an open source design and iterate on it… and contribute to the project while making bespoke hardware that perfectly fits your use case.”

How the 3D Chameleon System Works

The original Chameleon uses timed presses on a switch to decide whether to load, unload, or change filament. The printer simply moves into that switch during a G-code sequence. No wiring into the mainboard is needed.

Clem highlights why this works so well: the stepper gives “one vibration per second” while the switch is pressed, so the system tells you how long the press has been held without needing a screen or any extra feedback hardware. This keeps the entire system independent and easy to retrofit to almost any FDM printer.

Updating the Electronics

Moving to a Modern Microcontroller

The original board uses an ATmega328P—the same chip as an Arduino Uno. Clem noticed the chip is now listed as “not recommended for new designs,” so he migrated everything to an ATtiny3226. It’s faster, doesn’t need an external crystal, and is much easier to source.

Porting the firmware mainly involved redefining pins and removing all I²C-dependent code. “The unit is actively searching for those devices on startup… it won’t find them and then it won’t go any further,” so stripping those features keeps the new board simple and predictable.

Switching to TMC2209 Drivers

He also replaced the DRV8825 drivers with TMC2209 units. They’re quieter and more reliable but need a proper power-up order, so Clem added Schottky diodes to ensure the logic rail stabilizes first. This avoids unwanted UART behaviour and keeps the drivers in the intended mode.

Adding Temperature-Aware Cooling

Stepper drivers can heat up inside an enclosure, so Clem integrated a thermistor-controlled fan. A voltage divider feeds an analog input, and the firmware reads the thermistor’s Beta curve to determine when to spin the fan. During testing, he set the threshold low to check behaviour, noting, “If I touch the NTC… the fan will engage.”

Clear Visual Feedback

One common frustration with the original setup is losing track of which filament channel is active. Clem solved this by adding a row of LEDs. Rather than manually toggling them all over the codebase, he wrote a helper function that sets the number of LEDs needed for the current state. Anywhere the original firmware would have printed text to a screen, the updated version now drives the LEDs.

A PCB Designed for Hand Assembly

Clem spaced out headers, switched to user-friendly connectors, and arranged everything to fit inside a Hammond 1455 enclosure. “My version is made so you at home can assemble it yourself with just a soldering iron,” he explains. The enclosure gives the board protection and a clean way to route cables and airflow.

Mechanical Side

The mechanical assembly remains unchanged because it already works well. The only challenge is sourcing springs and bearings, which Clem notes can be easier in the US than in Europe. Still, all required parts are available and the printed components match the open-source originals.

Working With the Original Project

Clem walked through the original GitHub repository, reading the schematic, tracing the ATmega328P signals, and mapping each function into the new design. His workflow followed a simple pattern: reproduce the original behaviour first, then layer the improvements.

The new firmware keeps all core logic intact: watching the switch, measuring press duration, driving motors for load/unload cycles, and producing that one-pulse-per-second vibration for timing. The new features—cooling, LEDs, hardware changes—sit on top of the existing behaviours.

Using the Upgraded System

The new board can run from any 12 V supply, including the printer’s PSU. Power draw remains modest. As Clem notes, “1.5 amps is plenty enough to run this.”
The overall workflow doesn’t change: the printer moves into the switch, the firmware interprets the press length, and the changer handles filament movement. The same G-code post-processing flow still applies.

Clem demonstrates the full loading and switching process once the new hardware is assembled, showing that the upgraded electronics perform identically where it matters while adding clarity and reliability.

Wrap-Up

The 3D Brookesia brings the 3D Chameleon MK4 up to date with accessible components, a cleaner layout, better thermal handling, quieter drivers, and simple status feedback. Clem describes the overall effort clearly: “We contributed to an open source project by remixing the electronics and porting the software… with some new features.”

The project files, firmware, and design updates are available for anyone who wants to build their own or extend the design further.

Supporting Files and Links

- Github Repo for 3d Chameleon MK4 original version

Bill of Materials

Product Name	Manufacturer	Quantity	Buy Kit
3D Printer Filament, PETG, Black, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Orange, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Blue, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, White, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
Microswitch, M140T01 Series, SPDT, Roller Lever, Solder, 5 A, 250 V RoHS Compliant: Yes	Multicomp pro	1	Buy Now
ATTINY3226-SU	Microchip	1	Buy Now
STEPPER MOTOR, 1.8DEG, 5MM, BIPOLAR ROHS COMPLIANT: YES	DFROBOT	2	Buy Now
Power MOSFET, N Channel, 55 V, 47 A, 0.022 ohm, TO-220AB, Through Hole	Infineon	1	Buy Now
NTC THERMISTOR, 10KOHM, AXIAL LEADED ROHS COMPLIANT: YES	EATON	1	Buy Now
Evaluation Board, TMC2209 SilentStepStick, 2-Phase Motor Driver	Trinamic	2	Buy Now
1455N1201BU	Hammond	1	Buy Now

Additional Parts

Product Name	Manufacturer	Quantity
Springs
Screws
Bearigns according to original 3D chameleon MK4 BOM

2361595

Open-Source Multicolor 3D Printing Upgrade: Clem’s 3D Chameleon Remix -- Episode 693

cstanton — Thu, 04 Dec 2025 11:46:57 GMT

Revision 7 posted to Documents by cstanton on 12/4/2025 11:46:57 AM

Watch the Project Build

The 3D Brookesia

Clem set out to rebuild the electronics behind the 3D Chameleon MK4 so the system could be assembled with current parts, hand-soldered at home, and extended with new features. He kept the proven mechanical changer but redesigned everything around it, naming the result the 3D Brookesia after a small chameleon species. As he puts it, “We take an open source design and iterate on it… and contribute to the project while making bespoke hardware that perfectly fits your use case.”

How the 3D Chameleon System Works

Updating the Electronics

Moving to a Modern Microcontroller

Switching to TMC2209 Drivers

Adding Temperature-Aware Cooling

Clear Visual Feedback

A PCB Designed for Hand Assembly

Mechanical Side

Working With the Original Project

Using the Upgraded System

Wrap-Up

The project files, firmware, and design updates are available for anyone who wants to build their own or extend the design further.

Supporting Files and Links

- Github Repo for 3d Chameleon MK4 original version

Bill of Materials

Product Name	Manufacturer	Quantity	Buy Kit
3D Printer Filament, PETG, Black, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Orange, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Blue, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, White, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
Microswitch, M140T01 Series, SPDT, Roller Lever, Solder, 5 A, 250 V RoHS Compliant: Yes	Multicomp pro	1	Buy Now
ATTINY3226-SU	Microchip	1	Buy Now
STEPPER MOTOR, 1.8DEG, 5MM, BIPOLAR ROHS COMPLIANT: YES	DFROBOT	2	Buy Now
Power MOSFET, N Channel, 55 V, 47 A, 0.022 ohm, TO-220AB, Through Hole	Infineon	1	Buy Now
NTC THERMISTOR, 10KOHM, AXIAL LEADED ROHS COMPLIANT: YES	EATON	1	Buy Now
Evaluation Board, TMC2209 SilentStepStick, 2-Phase Motor Driver	Trinamic	2	Buy Now
1455N1201BU	Hammond	1	Buy Now

Additional Parts

Product Name	Manufacturer	Quantity
Springs
Screws
Bearigns according to original 3D chameleon MK4 BOM

2361595

Open-Source Multicolor 3D Printing Upgrade: Clem’s 3D Chameleon Remix -- Episode 693

cstanton — Thu, 04 Dec 2025 10:38:25 GMT

Revision 6 posted to Documents by cstanton on 12/4/2025 10:38:25 AM

Watch the Project Build

Supporting Files and Links

- Github Repo for 3d Chameleon MK4 original version

Bill of Materials

Product Name	Manufacturer	Quantity	Buy Kit
3D Printer Filament, PETG, Black, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Orange, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Blue, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, White, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
Microswitch, M140T01 Series, SPDT, Roller Lever, Solder, 5 A, 250 V RoHS Compliant: Yes	Multicomp pro	1	Buy Now
ATTINY3226-SU	Microchip	1	Buy Now
STEPPER MOTOR, 1.8DEG, 5MM, BIPOLAR ROHS COMPLIANT: YES	DFROBOT	2	Buy Now
Power MOSFET, N Channel, 55 V, 47 A, 0.022 ohm, TO-220AB, Through Hole	Infineon	1	Buy Now
NTC THERMISTOR, 10KOHM, AXIAL LEADED ROHS COMPLIANT: YES	EATON	1	Buy Now
Evaluation Board, TMC2209 SilentStepStick, 2-Phase Motor Driver	Trinamic	2	Buy Now
1455N1201BU	Hammond	1	Buy Now

Additional Parts

Product Name	Manufacturer	Quantity
Springs
Screws
Bearigns according to original 3D chameleon MK4 BOM

2361595

Open-Source Multicolor 3D Printing Upgrade: Clem’s 3D Chameleon Remix -- Episode 693

cstanton — Thu, 04 Dec 2025 10:29:01 GMT

Revision 5 posted to Documents by cstanton on 12/4/2025 10:29:01 AM

Watch the Project Build

The 3D Brookesia

A tiny chameleon species lends its name to an ATtiny-driven remix of the popular multi-filament changer. Clem develops an open-source redesign of the 3D Chameleon MK4, a system that adds multicolor filament-changing capability to almost any FDM 3D printer by using timed mechanical actuation rather than electrical integration with the printer controller.

Clem evaluates the original system and retains its core mechanical motion components while replacing the electronics, updating the drivers, and adding new sensing, cooling, and feedback features. The goal is a modern version built with currently available components and assembled entirely by hand.

How the 3D Chameleon System Works

The 3D Chameleon swaps filament using press-duration inputs. The printer activates an external switch using standard G-code movements. The controller board detects how long the switch is held and executes a corresponding load, unload, or change operation.

Clem explains that the motor “vibrates once per second” during the press duration, giving tactile feedback without screens or menus. This allows users—or the printer itself—to count the number of pulses and trigger the correct filament action.

Because the only integration point is a mechanical switch the toolhead bumps into, no modification to the printer’s mainboard is required and no extra signals are routed into the original control system.

Key Hardware and Firmware Modifications

Microcontroller Replacement

The original hardware uses an ATmega328P, mirroring an Arduino Uno design. The chip is now listed as “not recommended for new designs,” so Clem migrates the firmware to an ATtiny3226, a modern UPDI-programmable microcontroller.
The ATtiny3226 runs faster, requires no external crystal, and is easier to source. Porting requires remapping all pin assignments to their Arduino-core equivalents in the MegaTinyCore framework. Clem removes all unused I²C-specific functionality since the original firmware expected devices such as an IO expander or display during startup.

TMC2209 Stepper Drivers

The legacy A4988/DRV8825-type drivers are replaced with TMC2209 modules. These run cooler and quieter, but require proper power-up sequencing. Clem adds Schottky diodes to ensure the logic rail stabilizes before motor voltage, preventing detection errors and avoiding unwanted UART mode.

Thermistor-Controlled Cooling

Because the TMC2209 drivers and internal enclosure temperature benefit from active cooling, Clem adds a thermistor-driven fan.
The thermistor forms a voltage divider read on an analog pin. The firmware converts the reading using the thermistor Beta coefficient. When the measured temperature exceeds the target threshold (Clem uses 30 °C during testing), PWM is applied to a MOSFET (RFP30N06 / IRLZ44-type logic-level device) to power the fan.

A corrected MOSFET orientation is required due to a footprint orientation mistake during assembly, fixed with a small hardware bodge.

Status LEDs for Visual Feedback

The original firmware had no visual indication of the active filament channel. Clem adds board-mounted LEDs positioned along the enclosure wall.
A firmware helper function, similar to:

controls how many LEDs illuminate. Any part of the firmware that previously printed text to a display now calls this function. This reduces code duplication and gives an immediate indication of the active extruder.

Improved Connectors and Layout

To make assembly accessible for home builders, Clem reworks the PCB:

Pluggable screw terminals or headers are used instead of proprietary connectors.
All connectors are placed along the edge to simplify probing and debugging.
A Hammond 1455 aluminum enclosure is selected so the PCB slides in cleanly and exposes connectors on both ends.

This layout ensures easier maintenance and experimentation for users wanting to modify software or hardware.

Mechanical Considerations

The project preserves the original mechanical filament-handling subsystem, since its levers, bearings, and spring-loaded drives already function as intended.
Some components require sourcing non-standard bearings or spring sizes. Clem notes that certain parts are easier to obtain in the US than in Europe but still achievable with patience. Complete hardware kits are no longer sold, so builders gather parts individually.

Leveraging Open Source Resources

Clem checks the original GitHub repository for mechanical files, schematics, and firmware. The ATmega-based schematic is reviewed and replicated feature-for-feature before introducing new components.
The project embodies iterative open-source improvement: reproduce → verify → enhance. All changes remain compatible with the original design's philosophy—mechanical actuation, no printer firmware changes, and full G-code interoperability.

The new firmware keeps the original behavior: monitoring a macro switch, counting press duration, running load/unload routines, and providing motor vibration feedback. Clem plans to submit a pull request so the updated ATtiny version remains available to the wider community.

Installation and Use

The updated unit powers from a 12 V source or directly from the printer’s PSU. Current draw remains low; two steppers at 1.5 A total are sufficient.
Operation is unchanged from the standard 3D Chameleon:

The printer moves the toolhead into the actuator button.
The firmware detects press duration.
The motor performs the matching filament sequence.

A supplied post-processor inserts the correct sequences into G-code. This keeps the integration printer-agnostic and avoids editing mainboard firmware.

Clem demonstrates loading and changing colors using the new hardware, verifying that the updated electronics continue to operate exactly like the original system while adding modern reliability, sensing, and quality-of-life improvements.

Wrapping Up

Clem’s 3D Brookesia project updates the 3D Chameleon MK4 with a modern microcontroller, thermistor-controlled cooling, quieter drivers, improved board layout, and clear status feedback. The system remains fully open-source, compatible with legacy workflows, and optimized for DIY construction.

The redesigned hardware and firmware will be published to Clem’s GitHub repository, with a pull request planned for the upstream project so others can adopt or build upon the improvements. Users wanting to explore additional features or contribute ideas can do so through the element14 Community.

If you want, I can generate a shorter version, a social caption, or a diagram describing the system architecture.

Supporting Files and Links

- Github Repo for 3d Chameleon MK4 original version

Bill of Materials

Product Name	Manufacturer	Quantity	Buy Kit
3D Printer Filament, PETG, Black, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Orange, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, Blue, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
3D Printer Filament, PETG, White, 230 °C to 250 °C, 1.75 mm Diameter, 1 kg	Multicomp pro	1	Buy Now
Microswitch, M140T01 Series, SPDT, Roller Lever, Solder, 5 A, 250 V RoHS Compliant: Yes	Multicomp pro	1	Buy Now
ATTINY3226-SU	Microchip	1	Buy Now
STEPPER MOTOR, 1.8DEG, 5MM, BIPOLAR ROHS COMPLIANT: YES	DFROBOT	2	Buy Now
Power MOSFET, N Channel, 55 V, 47 A, 0.022 ohm, TO-220AB, Through Hole	Infineon	1	Buy Now
NTC THERMISTOR, 10KOHM, AXIAL LEADED ROHS COMPLIANT: YES	EATON	1	Buy Now
Evaluation Board, TMC2209 SilentStepStick, 2-Phase Motor Driver	Trinamic	2	Buy Now
1455N1201BU	Hammond	1	Buy Now

Additional Parts

Product Name	Manufacturer	Quantity
Springs
Screws
Bearigns according to original 3D chameleon MK4 BOM

2361595

Open-Source Multicolor 3D Printing Upgrade: Clem’s 3D Chameleon Remix -- Episode 693

cstanton — Thu, 04 Dec 2025 10:09:33 GMT

Revision 4 posted to Documents by cstanton on 12/4/2025 10:09:33 AM

The 3D Brookesia

How the 3D Chameleon System Works

Key Hardware and Firmware Modifications

Microcontroller Replacement

TMC2209 Stepper Drivers

Thermistor-Controlled Cooling

A corrected MOSFET orientation is required due to a footprint orientation mistake during assembly, fixed with a small hardware bodge.

Status LEDs for Visual Feedback

The original firmware had no visual indication of the active filament channel. Clem adds board-mounted LEDs positioned along the enclosure wall.
A firmware helper function, similar to:

Improved Connectors and Layout

To make assembly accessible for home builders, Clem reworks the PCB:

Pluggable screw terminals or headers are used instead of proprietary connectors.
All connectors are placed along the edge to simplify probing and debugging.
A Hammond 1455 aluminum enclosure is selected so the PCB slides in cleanly and exposes connectors on both ends.

This layout ensures easier maintenance and experimentation for users wanting to modify software or hardware.

Mechanical Considerations

Leveraging Open Source Resources

Installation and Use

The printer moves the toolhead into the actuator button.
The firmware detects press duration.
The motor performs the matching filament sequence.

A supplied post-processor inserts the correct sequences into G-code. This keeps the integration printer-agnostic and avoids editing mainboard firmware.

Wrapping Up

If you want, I can generate a shorter version, a social caption, or a diagram describing the system architecture.

Supporting Files and Links

- Github Repo for 3d Chameleon MK4 original version