Well I finally did it. I stumbled my way, cussing, through the illegible one-page "instruction manual" for my metal punch from Harbor Freight (which did not, in fact, have "screws", but rather metric allen nuts, for which no allen wrench was provided (rather, a big dopey "key" was enclosed); my set of course was not metric so I had to go the hardware store), and stunned myself by actually figuring out how to use it. Punched out some little discs from copper and brass 22 gauge sheet, hammered them a little, put holes in the middle with my pin vise drill, domed them to fit a 12mm bead, hammered them a little more, and oxidized them. Here they are, after a little polishing. Pretty much the way I'd hoped they would turn out.
It was a stupid amount of work. It's the drilling the little hole that's a pain. Think I'll make a little dimple first with an awl next time, maybe it'll go faster.
I have some 20 gauge sheet that I think would make some nice, really burly bead caps, but I don't think I could punch through it. I almost couldn't get through the brass sheet; might have to have the BF do that. It's rated for up to 18 gauge, but man! I would need an elephant to come step on it for me. I need a hydraulic metal punch. If anybody has any tricks for punching tough metal, I'd love to hear them. Maybe I'm not doing it right.
I would love to do this in silver too. I'm contemplating getting some silver sheet too, but I'm afraid it would be even harder than the brass. Anybody have any experience with sterling sheet and metal punches? The 22 gauge seems like a good thickness for bead caps. Probably too thin for charms or tags though.
OK, going to clean up my mess and drink a beer with the BF. I think I'm going to use the two copper pair for some green opal and maybe some aqua terra jasper earrings. I'm going to put the brass ones on a pair of faceted red agate earrings.