After a I saw a couple videos on the web about watch repair I bought a bunch of cheap mechanical watch carcasses and parts off of ebay for a few dollars just to see how complicated things like disassembly, cleaning and rebuilding actually might be. Frankly, it's not looking like a skill that takes a lifetime to learn if you're naturally patient, careful and you have some idea about how they work to start with - I'm already schooled in machine design so maybe I have a tiny head start. They come apart and go back together in an obvious, logical order. I have also been taking apart cheap quartz watches (analogue type) and customising them. At work my colleagues still haven't figured out how I got a watch with our corporate logo on the face (and they didn't), or why I keep denying that I own a Cartier Tank watch when there seems to be one on my wrist half of the time.