A lot of the guys are getting the basic pattern waterjetted, since a person needs a lot of badges this is usually pretty cheap. They are then rolled or formed between a few pieces of pipe to get the basic look.

If you want to attach a pattern to metal, my favorite way in this scale is to output a pattern onto laser, or output it from a photocopier. Place the ink side down on your steel and wipe the non-ink side with acetone, you will get a very detailed transfer. I think you can do this with heat to create iron on transfers. The acetone seems only to work once, so make several if you have to do the printing at a separate location.