You’re going to need more than that unless you’re doing a patch job. But I’ve read here that 7-10 good layers is a start. Really depends on how flexy you want the deck. I don’t exactly remember the thread but do some searching for fiberglass enclosures and you can a better idea of what you need to do. @eboosted does his own enclosures. Might could ask him for assistance.
The thin ‘e-glass’ style stuff like that is primarily used for a cosmetic layer right under the gel-coat or epoxy exterior layer. You want a heavier layup for strength and for layer height. It will take a ton of these to get a decent thickness. I’d recommend a 8 to 12oz biaxial s-glass cloth.
Oh my! what a topic. I’m all tooo familiar with using Bondo for making a box. ITs EXTREMELY effective. ITs also foul and terrible. but its cheap! and readily available. Just wear a mask stuffed with plague victims so it will smell better.
seriously though… 3 to 4 layers.
and experiment with the hardener first. You don’t want to get caught running out of time wetting fabric into a difficult angle.
i thinkk our boy is shopping the bottom shelf at walmart. He specifically mentioned bondo. The fabric for that stuff is simple low density cross weave but stacked up 3 or four layers thick will yeild a decently strong box. I used them for several months at a time before they started cracking at the bolt holes.