+1 Laitch. Filmcamera given that these parts are to block the heat from getting to the rider, manufacturing them should be possible. We have a shop called Clark Rubber ( US should have similar but better) and they sell varying thickness of high density foam rubber. Having seen these parts on a K75 RT 1/2" thick looks ideal. Armed with foam rubber contact glue, aluminium tape, Refectix and a contour gauge and cardboard to make templates it would be a challenging but rewarding project.
Regards Martin.