If you sandcarve on acrylic, you find out quickly that you cannot blast any real depth into it because the friction of the prolonged blasting partially melts the acrylic, turning it an ugly brownish color. Therefore, with this material use only the standard thickness of photoresist, which is 3-3.5 mils. The pressure setting is similar to the one for glassware, around 20-25 pounds of pressure with a nozzle distance of 6-8 inches.
Surface frosting is the name of the game with acrylic. You also have to be more careful in handling this material as it actually scratches easier than glass does.
—Ruth Dobbins, Your Professional Glass Consultant