Acrylic (known to its friends as PMMA, Poly[methyl methacrylate], Plexiglass, Perspex and so on) is widely used as shatter-resistant alternative to glass. Acrylic comes in two varieties: cast and extruded - both versions have advantages and disadvantages depending on the intended use. Cast acrylic engraves white with good contrast, while extruded is generally more consistent in thickness.