we drill all our holes with a dremel and a diamond core drill bit, using a container and a piece of glass as a bottom glass to make sure the drill does not get any slower or faster when going through our art glass. (See also Introduction to Glass Fusing, Pg. 29. I tried the putty ring, loosing all the water in no time and ruined my $ 8.00 drill bit in seconds.
petra kaiser – http://www.kaiserlee.com