I tried using Spam can to make caps. It mics at .012 thick. If you are careful not to go all the way down you’ll get one like on the left. If you drive the punch all the way you’ll get one like on the right and have a heck of a time getting it out of the die. I only ended up with the one before I stopped. I wanted to see if they would fit a nipple before I made more. It fits a rifle nipple just fine but it probably wouldn’t go on a revolver with all those points sticking out.
