Lexan Polycarbonate Flat Sheet are considered unbreakable

Polycarbonate plastic materials offer a great blend of beneficial features including high temperature resistance, impact resistance and optical properties position polycarbonates in between commodity plastics and engineering materials.
Polycarbonate is a very durable material. Whilst it has tremendous impact-resistance, it has lower scratch-resistance and so a hard coating may be applied to polycarbonate eyeglasses lenses and polycarbonate exterior automobile equipment. The characteristics of polycarbonate tend to be comparable to those of Acrylic PMMA materials, but polycarbonate is stronger, it is usable in a wider temperature range and is a bit more expensive. This plastic polymer is highly transparent to visible light and it has better light transmission characteristics than several types of glass.
Polycarbonate has a glass transition temperature of around 150 °C (302 °F), so it softens gradually above this point and flows above about 300°C (572 °F). Tools will have to be held at high temperatures, generally above 80 °C (176 °F) to help make strain- and almost stress free products.
Unlike most thermoplastics, polycarbonate can undergo massive changes in basic shape without cracking or breaking. Because of that, it could be processed and formed   without needing to be heated using standard sheet metal techniques, for example forming bends with a brake. For even sharp angle bends having a tight radius, no heating is generally necessary. This makes it useful for prototyping applications where transparent or electrically non-conductive parts are crucial, which can not be produced from sheet metal. Be aware that PMMA/Plexiglas, that is certainly similar in appearance to polycarbonate, but it's brittle and can't be bent at room temperature.
Polycarbonate is commonly used in eye protection, along with other projectile-resistant optical type applications that would normally indicate the use of glass, but require much greater impact-resistance. Many kinds of lenses are produced from polycarbonate, including automotive headlamp lenses, lighting lenses, sunglass/eyeglass lenses, swimming and SCUBA goggles, and safety glasses for use in sporting helmets/masks and police riot gear. Windscreens in small motorized vehicles are normally produced from polycarbonate, such as for motorcycles, ATVs, golf carts, and small planes and helicopters.

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