I use DigiKey, it's a bit less hobbyist oriented but you can find pretty much anything you'll ever need there.

I used KiCad to design and ordered from JLCPCB, it was a way simpler process than I was expecting

You can also use it as an input (kinda) without setting the fuse by using a voltage divider to keep it above 2v. It isn't super useful but it's nice for prototyping

I really enjoy trying to minimize program overhead because of this. Sure this project will run on most machines, but what if I could make it so compact that it could run on a potato? How small and efficient can I make this? It's definitely more fun than web dev (oh god why)

Gotcha! I usually get spools from Overture and they haven't let me down yet, so I'd probably recommend them.

Usually just normal PLA, it's good for pretty much everything and it's cheap. PLA+/PLA pro for anything that I think will need a little extra strength and it's also pretty cheap.

I mean I gueesss I can go on another Factorio binge

Aw nice, that's exciting. I can't ever figure out normal USB protocol so I wish you luck 😁

You can! I've messed around with this in the past and you can send serial data through the USB from the arduino to the pc, I processed the data sent with a python program. There's probably better ways but this way is pretty simple.