Design Nomenclature / Physical Model Making
PMMA
Also called acrylic, Perspex, Plexiglas, Lucite, plexi
A hard, optically clear thermoplastic that laser-cuts to a flame-polished edge and solvent-welds invisibly. Cast acrylic machines and lasers cleanly; extruded is cheaper, gummier, and crazes when solvent touches it. It is brittle — it cracks where a tougher plastic would bend — and it holds an edge under load until it doesn't.
In practice
Perspex, Plexiglas and Lucite are trade names in different countries for one polymer. "Acrylic" also names a paint binder, which is why shops that paint say "plexi" instead.