I sometimes watch a video by a YouTuber named "LOOK MUM NO COMPUTER", he does various electronics on old hardware which are mildly fascinating. Anyways, about two days ago he created a hardware controller for a SEGA Mega Drive: https://www.lookmumnocomputer.com/projects#/sega-megadrive-synth Admittedly, I'm not overly interested per-se, and I know a few people have done this before with mild success, though not exactly at this scale, but I thought some of you might find it interesting at least~
He does a lot of neat stuff with electronics and synthesizers. He's also experimented with the Master System, Gameboy, and even Furbies, too, just to name a few things.
Wait... Its arduino based? I might have to play with this. And yeah one of my favorite youtube channels.