Flasks and other items made from metal are popular these days; they have a similar restriction in terms of blasting acrylic. You can only achieve a surface frosting on these items, not because it will melt, but because it is hard enough to not allow for any depth. I suggest that when blasting any metal object, use the standard thickness of photoresist and a blasting pressure setting of about 25 pounds of pressure. If depth is desired, you will have to switch to a rotary or laser engraver.
—Ruth Dobbins, Your Professional Glass Consultants