I'll add another one to the list: automotive brake fluid.
An excellent container for the purpose is an aluminum foil cooking pan - the kind that are sold in packages of three or four, in various sizes, at the grocery. Put it in the kitchen sink, fill it to the necessary depth with brake fluid, and submerge the part. Within ten or fifteen minutes, the paint will start lifting off. Rinse it off under the faucet; that probably will take off any paint that's left. If not, go to work on it with an old toothbrush.
Brake fluid containers carry various safety warnings. I haven't gotten any burns or other skin reactions from it, but it will take paint off anything it hits. (That's why mechanics - if they're competent - always put rubber mats on the fenders of cars when adding brake fluid.) I don't know whether it's any more dangerous than any of the other substances mentioned already; all I know is that I've always had good luck with it.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.