Fan shroud questions.

Furyus2 try an aircraft composite supply place. But that may be expensive. You can prob trim out and use plastic trash bag as well. Anything like that the resin wont stick to. Maybe test try some resin on the tape and plastic film you want to use to see if when dry it pops loose easily.

I would not recommend using pam or anything oily as it will wick into the fabric and contaminate it, and it will be hard to get the resin to stick when you add fiberglass to the cloth later.