If you've spent ten minutes shopping for a splashback, a shelf or a shed window, you've probably seen the same sheet described as "Perspex" on one site and "acrylic" on another - often at wildly different prices. It's a fair thing to be suspicious about. So here's the honest version, written for people who just want to buy the right sheet without being talked at. Acrylic is the everyday name for a plastic called polymethyl methacrylate, usually shortened to PMMA. It's a rigid, glass-clear thermoplastic that's been around since the 1930s and turns up in everything from aquariums to aircraft canopies. According to the British Plastics Federation, PMMA is prized for its optical clarity - it transmits more visible light than glass - along with good weathering, decent impact resistance, and the ability to be cut, drilled, bent, and polished with fairly ordinary tools. That's the material. Every acrylic sheet you'll find in a UK plastics ...