Neat HOW TO from Ralis Kahn – Vacuum forming is simply heating up sheets of plastic until they are soft and stretchy then placing it over a positive form and using a vacuum to suck the plastic tightly onto the form. I have gotten very good detail with my machine, even pore texture from life casts! I had seen more elaborate machines with tanks, vacuum pumps, check valves etc. I just wanted to test the process and it worked so well that I have been using it ever since. [via] Link.