Well, that and the cool steampunkesque look. 
As for making them - well, I’m still working out the details (in conjunction with my wife, who makes jewelry from metal), but at the moment I’m thinking of cutting and folding copper sheet into the right shape (probably using an existing keycap as a form), then soldering the joints on the inside to keep it in place, and engraving the character(s) on the top surface. I’m still thinking about the best way to make the attachment to the keyswitch, though.