Inspired by Frederick van den Bosch's Forget Me Not Project I decided to build my own cat treat dispenser.
For me the main challenge was in the mechanics of it all, so having fvan 's design to help me out made a world of difference.
I picked up an old pop bottle, and I already had a fairly big servo I could use. For the mechanism I used parts from a $3 dollar store Meccano-knockoff kit.
In this picture, the unit is held up by my "helping hands" - normally used to hold things while soldering. I still need to build a platform to hold this for the final build.
The smarts are provided by an Arduino Pro Mini. It has a switch that you push to dispense the treats - ultimately this will have some kind of lever that we'll try to train the cats to use so they can treat themselves 
Maybe a future version will use a Raspberry Pi with webcam and remote dispensing for when we're away.
I power the whole thing using a USB power bank that contains an 18650 lithium battery. That seems to have enough juice to run it, though I don't know for how long. No need to be near an outlet that way.
Here is a video of how it works. I did try with treats, and tuned it to dispense just a small handful. After dispensing, the unit waits for 5 seconds before it will dispense again - that's to keep it from being abused by an overzealous kitty (it could happen!). The green light stays on for the time it is pausing, so I know what it's doing.
I also added some smarts to prevent it from dispensing again if the button has not been released - in case the button gets stuck on.
Cheers,
-Nico
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