I finally bought an airbrush and some powder. I found a good Youtube video where a guy first heats his small parts with a heat gun, sprays on the powder, and then heats it again to melt the powder until it flows out. I've done some sample projects and am quite impressed. This method is best for relatively small parts.
Since the parts are small, I found that, if I'm really fussy about the finish, I can wet sand the parts with 600 grit paper and then polish them to a very nice finish.
This sample pendant is just over 1.5 inches in diameter.
Here's a Youtube video showing the heat gun technique but he doesn't use an airbrush - he uses a home made fluid bed. Lots of other Youtube vid's if you go looking