One of the Acrylic Resins, it is Polymethyl methacrylate in solid form and is a permanent glass-like plastic that does not turn yellow. Plexiglas is used in many modern sculptures and can be cast and shaped by heating. Source: Ralph Mayer, "A Dictionary of Art Terms and Techniques"<br><br>A trademark for an acrylic plastic available in sheet or rod form. PlexiGlas can be transparent or translucent, and is available in many colors.Also see cellocut, fiberglass, Lucite?, polyester resins, and resin.