Yes, I do use a mandrel. I use the adjustable mandrel and regular bushings.
For the 1/4" hole, the bead fits nicely on the mandrel without brass or anything... For the next two sizes, I use a drill bit that gives me a hole perfect for the shoulder of either a Sierra bushing, or a Cigar bushing, etc. etc.
I actually got a custom order for some ear guage plugs that i will be starting on when i recieve the material. They will be wood.... Wood that was taken from Burning Man just before the fire was lit last year. With my new dreadlocks, I seem to have found a bunch of new Hippy friends!!