Maybe a bead or sandblaster?
What about a dremel sort of tool? With some rubberised burrs that are impregnated with abrasive material that can go from a course grain up to a mirror finish. I'm a watchmaker so I know about those sorts of things.
Loads of different shapes and grades of abrasiveness.
http://www.cousinsuk.com/default.asp...oductid=456319 Jeff