Black Powder Coated Bundt Center Caps

Occasionally I come across old metal center caps used on Bundt wheels which are pretty cool. I've always wondered what kind of metal they are, but I'm not sure. It seems like pot metal, perhaps you know for certain? Anyway, a while back I had a trial set of these powder coated black because I have an idea for setting up a future custom W114 on black 14" steel wheels with these fabricated into the front rims and rear hubs. I wanted to see how the caps would turn out before I did all the wheels. As many of you know these center caps are now made of plastic. So here's the trial set. They turned out great. Minor wear, but super......rare! Said it.