"Frequent Flyer" ID badge or item

Twice in as many months I've attended out-of-town events that included a pin or button used to identify experienced dancers. One was at a Jane Austen ball, where the local ECD group brought in acetate convention name badges that contained an illustration of two dancers. The other was a Civil War event where the dance troupe floor managers wore small cloisonne badges. This seems like a good idea to have at events with lots of visitors. At the Austen event, everyone who "knows what you're doing" was invited to wear a badge, and newcomers were encouraged to select them in partnerships. At the other event, dance troupe folks were busily explaining the basics to folks who already knew the drill, and having something available for the public could have advanced the conversation along. If you were designing something to use in this regard, what would it look like, and be made of? Thanks for ideas! --Karen D.