ok as i gather info on my quest to form i guess i will need some thing that can resist a temp of 400' f and that is being on the over cautious side but with that said what would be a good material and thickness to use it is going to be about 20"x24" x4" is the rough size of the cover i will have to get down and dirty to get the exact dimensions but that is the rough idea of it so thanks in advance jason