Fan shroud questions.

Its a great writeup on the fan shroud, except 1 thing the fiberglass is going to stick badly to the masonite board making it very hard to get the masonite board out. I have access to a release film plastic specifically used for fiberglass vacuum mould repairs. I will probably use this release film on my masonite board , not because i want to save it or anything, but because it will make it easier to remove the shroud once the resin dries.