I am thinking of making my heated bed using a glass cutting board which should be tempered. There is a very fine Morie (hair like pattern) on one side and smooth glass on the other. The pattern side is very shallow about 0.01" deep. I think this may help in holding the parts to the glass instead of sprays or glues. The only problem I see would be the cleaning but could be done with some steel wool or MEK. but from the sounds of it a dirty bed may have its advantages for other posts I have read.