As a shatterproof and versatile stand-in for glass, polymethyl methacrylate (PMMA) -- commonly known as plexiglass or acrylic -- has become an invaluable and nearly indestructible part of the culture.
Commercial production of acrylic glass began in 1936. One of its first applications, reports eplastics.com, was to make aircraft windshields during World War II. Acrylic was bulletproof and able to withstand the extreme wind velocities. When heated, it could be easily formed into shapes that fit the aircraft window designs.
In most applications, acrylic is shatterproof with "six to 17 times greater impact resistance than normal glass" reports rplastics.com, able to withstand a compressive impact equal to 18,000 lbs per square inch (psi). Acrylic will break if subjected to force beyond that measure, but "breaks into large relatively dull edged pieces which disperse at low velocity, due to the light weight of the material."
The inherent strength and ability of plexiglass to resist force makes it a key part of countless products. Examples include protective spectator glass in arenas, bulletproof glass in banks, aquarium and display-case glass, safety glasses, dentures and even artificial fingernails.