Arduino has such a nice USB HID library that making the embroidery-hoop steering wheel for American Truck Simulator was pretty easy. I'm thinking I might want to make a bunch of custom input devices in 2021 - a bunch of fun, silly, or very-specific controllers.
It's the sort of project where it would be useful to have a definite deadline for each one (an implicit quality ceiling for prototypes, kind of), so maybe like 1 a month?