How I made my fiberglass box...
Here is the stock trunk. Under the lid, there is a spare tire... remove that and the jack.
First, i measured up a frame out of MDF to place inside the trunk. Put the frame in and mask off the area in which you will need (around the frame) and Cut out the carpet of the stock trunkliner, as shown.
Fiberglassed that stock carpet (like 1/2 galon alone), added about 6-10 layers of Mat, and braced with 3/4" MDF (optional). The bracing is cut the way it is to help aerodynamics and cut down on extra weight.
made a top peice, simply. Just cut a where you want it to go on the frame to the exact size, screw it down, cut out your subwoofer baffles, mount them using plumers tape, and possition the subs just right.
stretch fleece nice and tight and staple at the bottom. The tighter, the better to soak up resin and keep out the wrinkles.
Here is after fiberglass resin (let sit in the sun to get it a little runnier to get it into the fleece). Adding a few layers of mat for strength... For best results, only do fiberglass matte inside as thick as possible, and do even layers of fiberglass cloth on the outside. This saves on bodywork later down the line!
after adding all the layers until strong (like 10 layers later) add body filler, sand w/ 40 grit, run filler puddy accross the entire surface, 100 grit, prime it up, 400 grit wetsend, and a final coat of prime.
Paint the box carefully. The basecoat should be done in thin-medium coats until even. Wetsand with say 600 grit and do one last coat. If you feel the need, wetsand with 1000 grit on this last coat. Then clearcoat as many coats as you can afford (well, 6-10 coats is awesome). Wetsand with 1500/1600 grit until smooth and even, then 2000 grit or higher if you can find it. apply your polish and buff away.
Beleive it or not, this was spraypaint from WalMart!
Buffing makes it happen. Take your time, it will look like candy.
Since i left a blank area for an amprack, lets take a look at how to do that...
Mount the amps where desired. Then, cut an MDF peice that can go over the top of the amps, yet take up the space you need. Use wireties (zipties) to make sure wiring is not going to get in the way of this.
First i masked off the section. Then, layed down 3 layers of matte, minimum. The more layers, the less chance for it to warp. I recommend 5-6 layers!
Cut out the desired shape, and test fit. Once you think its good to what you are after, its time to get the amps flush mounted.
for whatever reason, i forgot to get pics after this point. But here is what goes...
Make, our of about 1/2" MDF, peices that follow the edges of the amp, but still allow wiring to go through as normal. Remember, it will go from the top-down, so make sure they will fit going downward.
After that, tape them into place on the amp (flush) and add 3 small peices of fiberglass matte to each end to attach to the base board. Make sure its dried well before removing. Remove and reseat a few times times to make sure it goes in there just right (not hitting amps or wiring).
Stretch your fleece and fiberglass. Cut out where you want the amps to be seen. Put body filler all around and sand.
If you see that a newer test fit is not setting on the sub box very well anymore, dont get mad! Its fixable! Just simply mask off the box again, and shove body filler in all the cracks.
do what you did to the box for filling in the imperfections. Paint if desired.
This is the final product. This is just black primer... For best results without a paint gun, use Dupli-color sandable primer-filler rattlecan primer (as it looks sexy and fills in great, and easy to put on!)