My Canon DSLR camera bodies are made with glass filled plastic over aluminum skeleton. What is glass filled plastic? It doesn't have the same cheap feeling as common plastic items. I've seen knife handls made with glass-filled nylon, and it is very hard. Is it like fiberglass, or microbeads? I imagine it uses that with some kind of thermoplastic as opposed to resin, but does anyone know what kind of plastic?
Current Canon bodies are made of anything from glass filled polycarbonate, to the same kind of engineering grade plastic that the light boxes of all current DSLRs, including the flagship models such as the Canon 1D X and the Nikon D4 are made of, to magnesium alloy.
Canon pioneered the use of glass filled polycarbonate materials in cameras way back in the film era. The first use of the material was for the lens barrel and some of the other non-optical components of the 50mm f/1.8 lens that was the standard lens for the Canon AE-1. Not long after that Canon and others started using the material for body panels and the like, with an aluminum skeleton and an all metal light box. Today the metal light box has been replaced by more rugged composites made by combining one or several different engineering grade plastics, such as Nylon 6-6 or Ultra-high-molecular-weight polyethylene, with other materials.
It's probably a glass filled polycarbonate. Composite materials like this get the benefit of the two different types of materials used to make it - it benefits from the polymer matrix as well as from the glass. According to the bottom link the glass improves impact, moisture, and chemical resistance of the polycarbonate.