I've made some hobby stuff with kydex. Knife sheaths, etc. Really neat stuff. Heat to 225 and it becomes soft. Drape on complex objects and it takes that shape exactly. Sandwich between a couple of towels and stack a few books on for light pressure. As soon as it drops below a certain pressure, it sets up in that shape permanently.
DIY larger objects like interior panels would be challenging. First, you will need an oven that large. I have tried spot heating with a heat gun without success. Second, you need a continuous surface as a mold. If your interior panels spanned gaps between ribs or bulkheads, it would take a lot of work to mock up a mold. Kydex picks up any tiny variation in the surface, especially with thinner stock, so everything would need to be a close fit.
For smaller projects, 12"x12" squares are cheap and readily available on Amazon, so nothing lost by a little trial and error.