I take some spongee rubber packing material that is smooth on one side and sort of egg crate on the other ( Procharger uses it for packing material) put it over the trans with egg crate side toward trans and use waxed freezer paper on the top side--apply layers of glass overit

End up with panel that is about 1 to 1 1/2 inches clearance from trans
Use as many layers to get thickness you want/need

Pull out chunks of sponge after cured--about the simplist way I have tryed in my 67 years( On 3-13 )