I made gears for a few years (no experience required!, learn on the job), and ended up knowing way more than I thought possible about the involute gear form, be

I made gears for a few years (no experience required!, learn on the job), and ended up knowing way more than I thought possible about the involute gear form, bevel gear generation, helical and spur gears, etc. I didn't have a computer at work, I did have a $10 Casio calculator I used to verify gear ratios, etc. In one of those civilization reset type of scenarios, I'd likely die quickly, but if I managed to survive, I'm teaching how to make gears and analog computing systems from them. I'm one of the odd birds who knows how to make Slide Rules, and compute logarithms by hand.