"I may have screwed up…I laminated all the layers up with Lam resin…??? I’m wondering how I’m supposed to foil it. Isn’t it going to gum up the sander BIG time? "
dont worry about it… the purpose of the wax in filler resin is to form a airtight seal over the resin as the outer surface layer wont go off exposed to air. you can just do the whole fin panel with lam then put a layer of gladwrap on it before it gels and its sandable too… when i made 40 sets thruster fins a day for a job i used a diamond tipped bandsaw blade. i would get approx 2 months of work out of it before sending it back for resharpening…