Here's a pic of a piece I made but never used. It's a piece of foam I shaped and wrapped in duct tape. I started with a block of foam cut in the general shape and pressed it in place. Then I sanded the block to shape and wrapped it in duct tape. I then layed cloth over it and trimmed it to fit. Never ended up running it because it was a little too flat to match up with a lowered bracket and the sides were a little too narrow, but you can get a general idea.
Best thing to do would be if you know someone who has one, coat it with PVA, glass over it, and pull the part right off that. That's what I would do