DIY Memory Cells?

Okey, I'll start with a gameboy. But I have an original from one of the earliest. Can I break it by failing to program?

Well you have to open it and possibly solder stuff to it. Get a spare one or two just in case.
Just to put things in perspective, a couple of old Gameboys will cost less than just the rest of the tools you'll need and far far less than what it would take to start from scratch.