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Discussion Starter · #1 · (Edited)
This is a project that I did about 2 years ago and have just now gotten around to writing a how on it. I don’t have a quantity of the list of of materials only because it was so long ago.


Fiberglass matt (fine woven) at Wal-Mart for about 5 buck

Fiberglass resin (buy the big gallon, better deal) at Wal-Mart about 15 bucks

A lot of cheap brushes

Disposable gloves (keep your hands from getting sticky)

Paint trays (I used these to mix the resin and hardener)


Aluminum foil

Mdf wood

Dowel rods

Bondo + hardener + glazing putty

Filler primer

Hot glue gun with glue sticks

Fleece (1.5-2 yards should be enough)

Paint (whatever you want, I used wrinkle paint to match my trunk but anything will do

1. Tape up the area in the trunk with aluminum with aluminum foil, it protects your carpet. and allows for the removal of the template

2.) Lay down one layer of fiberglass and paint on the resin with the brush. Allow enough time to dry. This is the template layer. You will be adding layers to the inside part of this mold to beef up the fiberglass. It’s recommended about 6-8 layers of fiberglass.

3.) When you have enough layers, you need to make your mdf ring, I will provide a website that shows you how to make them. After you’re made your ring, glue the dowel rods and the mdf ring in the position shown in the picture.(Fiberglass Subwoofer Box)

How to make circular rings

or you can have it made at a wood working shop

4.) After you have this done lay the fleece over the ring + dowel rod rigging and hot glue it to the back of the box. This takes time; you need to be careful so that you do break the glue holding the dowel rods and mdf ring together.

5.) Mix some fiber glass resin and dab it onto the fleece. Be careful not to dab to hard. Give it a good two coats. We just want it hard so that we can lay fiberglass over it.

6.) Next, cut out the hole where the speaker is suppose to go

7.) Lay fiber glass over the face of the box. 6-9 layers of fiber glass should be thick enough

8.) Once it dries, sand the face down smooth, fill in spots with bondo, glazing putty, etc. I am not going in depth with body work.

this not the same box but the box to the other side. i am showing the primer

9.) I do not have any pics of installing the speaker connection in the back. Its pretty straight forward. Find one that square, cut the square in the back of the box and seal it. Easy


the finished product. please excuse my dirty ass trunk :wavey:


Banana suit what?!
1,243 Posts
Those look awesome. About how long did that take and what's a rough estimate on total cost? not including the subs :D If you don't remember that's ok I was just curious if you did

3,936 Posts
Looks awesome!

Premium Member
8,831 Posts
great write up

i may try this soon!
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