Had to look this one up in case it had not been mentioned earlier////
Polymethyl methacrylate (PMMA), a synthetic resin produced from the polymerization of methyl methacrylate. A transparent and rigid plastic, PMMA is often used as a substitute for glass in products such as shatterproof windows, skylights, illuminated signs, and aircraft canopies. It is sold under the trademarks Plexiglas, Lucite, and Perspex.
Google this for a link to some interesting info ---------> PMMA Injections & Bodybuilding
I are dumb because I have never heard of PMMA injections before this morning. And I have also not read most the posts under this topic ... so excuse me if this has all been mentioned earlier.