[aerohead]

Most automakers use it under their vehicles and in the wheel houses.
It's typically pre-conditioned, then vacuum-molded, while air-clamped over a hollow pattern ( which can be wood ) riddled with bleed holes, directly after leaving an electric oven.
After cooled, sent to a trim fixture where a pin-router removes any excess material or cuts open NACA inlets ( as AUDI uses ), etc..
It doesn't have much strength as a flat panel. Corrugations can be formed in for rigidity. Or strengthening structures hot-air-weld-bonded to the 'unseen' portion.
I'm unsure where an individual would purchase it. It's a commercial / industrial product, sold by the pound by a jobber. There might be a business card and minimum purchase order requirement for procurement.
We used to have a marine plastics manufacturer in the area, which gave me a complete tour of their facility and all operations, who volunteered to allow me to purchase small amounts and 'rent' their facilities for after hours production of my own, if I'd supply my own tooling.