I wouldn't think of a real mechanical type of tinkering, others can. for me it's usually some type of woodwork, or sight work. stock refinishing/cut down, recoil pad,re-shaping a grip, along those lines. sometimes it's just to learn about a type of gun I've never owned, or job I never attempted. usually I try it out on a cheapo specimen first. the older I get the more expensive the learning and mistakes become. I've never been able to leave "real good enough" alone. the last real dum/dum was using my homemade electrolysis cleaner on a vintage 1952 Marlin waffle top lever I just had blued, and lost an inch of bluing off the muzzle, cuz I just couldn't wait to find an old junker to try it out on.