Personally: Hiking, biking, photography, DnD, and fixing things.
It sounds like a lot (because it is lol) but with ADHD having a group of hobbies I can orbit around (especially if they can overlap (like these ones))can help me avoid diving into too many new hobbies.
3d printing is useful for almost any hobby if you try hard enough!
We got really into making handmade dice for a while there, and used our resin printer to make custom master dice with our logo on. And I’ve used it to print out useful bits and bobs for cross stitch too. Someone I follow on Mastodon 3d printed a sock knitting machine, that was very cool.
Truly 3d printing is the hobby that keeps giving!