You can use ABS Plastic it comes in sheets and can be heated with a heat gun and moulded to any shape you want. You can find it at ant custom stereo installer, they use it for making radio trim and tweeter pods or what ever. I once made a boost gauge pod out of it, it work out well. I do recommend getting a good pair of gloves if your going to be hand forming.Jake said:Is there such a thing? I'm not happy with the CAI systems that have come out and am interested in making my own. Does anyone know if there is a thin rubber or plastic that can be heated (heat gun) and formed, and retain its shape once cooled?