Hey brother, I make helmet shields as well. The shields from the fire store are most likely vinyl and I'm not even sure the "gold leaf" that they do is real gold leaf. Seems like a vinyl as well. I've tried to mess around with the gold leaf but haven't got it down just right. With real gold leaf the shield would have to be pre-bent or else when you go to shape it the gold leaf will crack.
As far as the graphics over top of the gold leaf, what I have tried is completely tooling out the shield and then laying the gold leaf on the shield. Then just paint over top of the gold leaf. A top coat will seal it all in. I'm going to mess around with it some more and if I find anything else that works I'd be glad to share.