i am going to have to DISAGREE with all of you
i built a spare tire well enclosure for 2 12s (the ones i am sellign now) and it was very easy. before that i had only worked with fiberglass one.
if properly braced, you dont need more than 1/4" of fiberglass. they key thing is BRACING. you can use peices of wood (1/2" square pieces are easy to cut and easy to place. you can also use rope. just let it soak in resin for a few minutes, then place it down.
as for cost, with 4L of resin, enough catalyst for said resin, a few yards of fiberglass cloth, and 2" wide 3M masking tape(MAKE SURE it is 3M, other stuff is CRAP), my total was about $120, including wood for the baffle. and thats canadian dollars, not yankee money
there are several web sites with instructions on how to do it, just do a search on google.com or the like.
just a tip, use 2" masking tape to mask the tire well. some people say use garbage bags or foil, but the resin will seap through the cracks. i used 2 layers of 2" wide 3M, and then topped it off with mold release (just painted 2 layers on with a paintbrush, the mold release costs around $10 for a half litre).
it took me 2 days to build it, letting the first layer cure overnite, and when i was done, it popped right out, hugging every contour. the well in my beretta was 2.2 cubic feet. easiest way to find out is to fill the fiberglass box with water. you will also find any leaks with this method, so its a good idea to do it outside.
wow, my fingers are tired
