It is possible, at work I deal with acrylic more than I like to. A good cooling system is required. Ours is air cooled, most engineering millers will be liquid cooled. Special acrylic milling bits can be bought which leave a better finish than a standard bit would leave, or a diamond bit can be used to leave a pretty much clear finish. We use flam polishing on any acrylic we cut but this is not ideal for something like a gear box, due to small holes and tolerances. The heat would warp it all. A chemical dip would be better.