I got a LiteVNA 64 a few months ago. A 'NanoVNA' style thing, goes up to 6GHz(with varying results near the top, but for the price, it's amazing) When I got it, I measured every single antenna I could find, felt like I just got the coolest and most useful thing ever, and then haven't used it since. I can feel it will be a lifesaver one day, but that day doesn't seem to be getting much closer.

vmate Congratulations on the LiteVNA.  I also don't use my NanoVNA often, but when I do - I use it for days on end either building something or troubleshooting something.

The LiteVNA looks amazing. I have a NanoVNA and I feel the same. I used it for a bit to test antennas when I got it, and then shelved it forever.

I know I have plenty of tools I’ve only used once or twice, but they were worth it for that, like the gauges and vacuum needed to set up my heat pump (during Covid shutdown- I had no choice but to diy it !)

My main unused tool is sadly my oscilloscope! Is a great unit, but other than a bit of testing and experimenting I’ve never needed it. Probably the worst part is that I did really need it to figure out a few problems, but by the time I got the oscilloscope those problem projects were already in the past. I’m pretty sure I’ve got other tools similarly purchased after I needed them.

The other main tool I’ve never used, other than testing it a few times, is my CNC router- I’ve never had the time to figure it out well enough to create something with it. And it’s so loud and messy (and a bit dangerous) that I can’t easily test it in the house.

I've got several USB logic analyzers that I never use. I regularly get tempted to buy a new, more powerful one, probably because in my head I keep coming back to that one time when I was writing a low level SD card library for a microcontroller and it was extremely helpful to debug the individual bits being sent between the CPU and the SD card. At that time I had a very extremely bare-bones and slow analyzer (it was a custom mode for a DSO Quad) and I had to slow down the communication speed quite a bit to debug it, but it helped me tremendously.

However, it's been like a decade since the last time I've done anything like that, and I haven't even touched the last analyzer I bought except for when I took it out of the box to test that it worked.

Same here. And I hope we never have to use it !

when i was at school i wanted a drill press

10 years ago i got one for home

as yet i have not yet set it up or used it 

I have an Intel Galileo dev board here amongst the growing collection of mothballed technology.

I have an Intel Edison board that I wish I had used but never really did anything with them. A bit sad though, they are very capable boards, but their development ecosystems are probably dead at this point in time. Luckily I made my own local mirror of the last version of the Edison repo I accessed and it's probably in one of my backup drives if I ever want to do anything with them (unlikely).

Oh no. Let's not start including dev kits! That could get very messy.