This should be interesting. Besides sharpening, what are the hobbies you enjoy that require some sort of precision. Mine are archery and woodworking. I could include golf as well I guess although I don't play anymore, got burnt out in college,
I enjoy working with metal. I'm not the greatest as I don't get to practice often enough but it's always fun creating something. Guns, although I don't get to play with them much since I live in the city right now. Doing all the work to my truck and the wifes car. Keeps the repair bills a lot lower and I get to use my engineering mind to figure things out.
A couple photos of some metal work:
Almost forgot....fly fishing and tying my own flies to fish with.
Knife sharpening (of course). Cutting stones, Fountain pens. In the past - whitewater kayaking, slalom racing automobiles. Microvascular surgery, hand surgery and neurosurgery - not hobbies but it did require some precision Tech support assisting my wife making jewelry.