I did it! Thank you for the inspiration and encouragement!
I was gonna use Cosmos for the case, but when I went to download my final design, it kept erroring ๐ So, I went with Skeletyl instead. It's designed around a PCB, but I hand-wired it instead.
I took inspiration from a Joe Scotto video and got away with using one microcontroller by connecting the two halves with a network cable (plus one extra wire because I needed 9 total). I can only include one image in this reply, but might make a post about the build with more photos.

Thanks! Haha I did!