Ok-kind of an odd question but.....I'm building a fiberglass enclosure in my spare tire well. The problem is that i've forgotten how many layers i've layed (**** fumes!). I'm guessing it's around 2 layers of cloth and probably 4 layers of mat, again guessing. I took the thing out and stood on it without falling through (good sign). Is there any way to tell when an enclosue is strong enough. It's only for 1 sub recieving about 350 watts. **** Fumes!