Make a Fiberglass Speaker Enclosure





Introduction: Make a Fiberglass Speaker Enclosure

This is an addition to my first instructable, it go's into much more detail about how to make the custom speaker box. This thing is a fully fiberglassed enclosure with 2 15" woofers, 5 tweeters and 1 mid range. Its powered by a deep cycle battery and is used with a dual lane 2400 watt amplifier located inside. It has a car stereo that controls the volume and the music. The backrest is covered in purple felt and lined with a rubber strip. There are 2 sets of lights on the back with a total of 50 leds each of blue and red lights with a controller box located under neath the speakers.

Step 1: First Get Supplies for Fiberglassing

Remember this is what i used for mine you have to judge how much you will need.
You will need:
Concert Speaker (Any will work)
2 Gallons of fiberglass polyester resin
6 Yards of fiberglass matting
3 yard of polyester
4 big tubs of Bondo
Particle Board
Speaker Wire
Car Amplifier
Car Stereo
Tools I Used:
Staple Gun
Nail Gun
Reciprocating Saw
Spray on glue
Bondo Spreader
Lots of Gloves

Step 2: Make the Frame for the Design You Want

First make the frame for how you want it look, i wanted mine to be a big box for loud sound and I wanted it to look wild. Try not to make such a hard design as like I did in the middle with the odd speaker sticking out in the middle because i spent alot of hours fiberglassing and bondoing that thing.
We made the base of the speaker box a rectangle with the front two corners rounded for a nice look.
We then added that thing that looks like a shark fin, that is there for the shape and added support.
As you can see in the second photo we had to cut out a ring that would be there to make sure the 15" sub would fit. I had to use a nail and a piece of string to make the ring an approximate size. I cut it out and filed/sanded until the speaker sat it in snug. We used posts to hold the speaker ring were we want it to be in the final design. The other speakers we did the same thing by cutting out rings to fit the other speakers and had them suspended by the posts. The frames for the speakers have to be abled to hold the weight of the stretched polyester. We then added a back to the box because we wanted that to be flat. You should wire now depending on how many speakers or how much access you have to the inside of the box after.

Step 3: Drape the Polyseter Now

Now that you have the frame up and wired you can now start to stretch and staple the polyester to the box.
Now i do not have a picture of the fabric before I fiber glassed it but it basically looked the same as the pictures.
When your stapling it to the box make sure that there are no wrinkles or its gunna be more work later. Start from the top and work your way down. As you can see in the pictures we had to go and get more polyester because we didn't have enough. We had that obstacle in the top part of the speaker box we had to put polyester over it after we had finished the other two sides.

Now that you have the polyester on the frame we need to harden it to make it workable. We now had to mix the polyester resin with the catalyst. REMEMBER do no use too much catalyst, i used to much and the resin got so hot that it got burning hot started smoking and instantly hardened, and didnt smell nice either. Once you have it mixed up paint the resin onto the fabric and make sure that the fabric soaks it up well. We waited a full day and tested to see if it had dried with a mixing stick, once we knew it was dried we made another batch of resin and cut 2"x6" strips of fiberglass and started painting them on. If you can paint the fiberglass on horizontaly and when you do the next coat do it vertically. When you are doing this try to make sure there are no bubbles or clumps of fiber glass, its worth taking the time for this instead of spending twice as much time later.

We only did 3 coats of fiberglass, some people say to use up to 7 coats but we felt like it would be strong enough and it turned out it was : ).

Step 4: Start to Bondo

Now grab your bondo and your gloves and start to cover your fiberglass in bondo, we found out the best way to do it pretty much when we were done. Try to get it as smooth as you can and as thin as you can while it still covers the fiberglass. It starts setting in around 3-4 mins so you have to work pretty fast. After you have sufficiently covered the box in bondo it is time to sand, wear a mask mostly because you might start sanding the fiberglass and you cant inhale that. Sand it down to the shape you want with 150 grit. We somtimes would sand on a fiberglass bubble and would have to bondo it to make it smooth again. After you have it how you like sand it with 400 grit so its perfectly smooth.

Now you need to cut out the holes for the speakers, for the big ones i used a reciprocating saw and a file and for the little ones i used a 2 3/4 inch circular drill bit. Make sure the speakers fit before you paint.

Step 5: Paint the Box

I chose a purple and yellow theme. For the paint I used some automotive spray paint primer and some purple krylon. I did 2 coats of primer to make sure it was on the box sufficiently. I then did 3 coats of purple. You can if you want use Clear Gloss Enamel, I used 2 coats of that to protect it and give it a nice shine. Now all you have to do is install the speakers and it should be ready to go!! If you need any help or would want me to put a less complex fiberglass tutorial up please comment.



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    Can anyone help me im trying to fit a sundown x10 woffer n a chey 1500 single cab any suggestions

    Can you give a ballpark estimate of the cost for the bondo, resin, matting, and polyester, in the amounts you used? Thanks.

    7 replies

    the bondo was about 70$ i used alot more then i needed tho The matting was like 20$ i only used around 4-5 yards The 2 gallons of resin was 100$ The polyester was like 25$ total

    Thanks man. I've been thinking about changing a curve on my car's body, although I'm not sure how well fiberglass fares in dents and such.


    Fiberglass is very hard expecialy when u use bondo on it and other people have done it so im sure it will work nice

    If you really want to change a bodyline nothing beats a hammer and a welder....bondo detaches from show cars all the time so be aware.

    I've been making show cars for years. if you don't want to use straight fiber glass use a thing called dyna glass its stronger than bondo but weaker that fiber glass. it would be easier to weld a piece of metal for the basic curve than layer it. if you don't know how to use bondo i wouldn't recommend it.

    there's a new technology using woven bamboo instead of fiberglass so you don't get skin irritation like working with fiberglass, and it uses less harsh chemicals too. as far as i know, it's only sold by a surfboard kit company.

    the article i read on it in some magazine mostly about building robots made it sound alot nicer to work with than fiberglass. i thought the chemicals were expensive for it, but they look about the same as fiberglass now that i've seen this instructable.

    would like to see more views of your completed project from the back & sides.

    cool build

    oh... i see the ghetto blaster trike thread in the margins now. looks wild!

    can i replace the hardener with superglue or something???
    i really cant find a good hardener at our not because i miss used it,cause i tried 1:1 ration..and 1:2 or even 1:3 ..2 and 3 are the ratio of hardener....but it dosent work at all....even if i add some catalyst in it.....

    can some one please help me.....any one???

    1 reply

    i do not think superglue would be a good substitute but all the bondo and resin came with a hardener made for it, you could try to order some offline but other then that i do not know

    it is the same person on the same day, i think he might have the right to steal his own pictures.....or does he

    By the by obvious observational skills is obvious

    I definitely think this is the very same project!! Sorry dude, no offense, but i'm just trying to make it fair for those of us that are really creating a new project.

    1 reply

    its completly different, i didnt just throw a pair of ipod speakers on a bike

    Dude, the Make A GhettoBlaster Tricycle was already done before te contest was published, I mean, is a relly good project you just can't pass by, still ripping those nice speakers apart was really really heartless.

    Great Job. That is pretty cool. I have a question about the fiberglassing process . Is the shaping of your item done by shaping with the fiberglass or is it done by how you sand the bondo. I want to make some fender flares for my truck and there will be convex and conclave curves on them I am planning. Not that I am trying to make it had on me for my first project of course. Since the flares are a little smaller scale than the speaker box, is there any problem if I use something like the dense insulation blue foam as the structure instead of a frame. Thanks.

    I'm thinking the particle board should be replaced with card board.