As far as making actual holes in a tank, i"ve only done 3mm glass. For testing and playing around I've done some 2mm and 5mm glass but nothing that I applied in a tank. From the sounds of some of the RC guys, the increase in glass thickness makes the cutting time increase almost logarithmically. I think if I needed a 10mm tank drilled I'd rather carry it out to Jack and Wendel on my back (from North Van to boot) than try Dremeling an overflow hole.
