I just ordered a 10mm glass hole saw from red tiger. It was pricey, but it should hold up for a long while. So my next question is: who uses a portable drill guide to drill 10mm holes in 1/4" glass? I'm wondering if I can get away with doing it by steady hand and patience. I don't want to spend an extra $40 for nothing, but on the other hand I don't want to crack $40 worth of glass. Thanks for the help.