More links, minor changes, price estimates, etc. Enjoy, let me know if you actually try it or need help! I'm more than happy to do what I can. I'm considering making a foam mold this summer and making up a few of these for members, if there is interest. It would still be relatively expensive due to the cost of materials & shipping, but I'd be doing it to help out members more than for financial gain.
I'm an amateur by all standards, but my box came out reasonably well so I thought I'd give you a half decent DIY. Unfortunately I did not take many pictures during the first half of this build, never expecting the final product to be DIY worthy. Maybe I'll do a new one this summer.
Cost is around $100, varying greatly if you already have most of the little stuff, or can get MDF in less than a sheet, or don't have all the necessary tools/safety equipment, etc.
No single step in this project involves anything difficult, so as long as you are willing to devote lots of time (most of it in small chunks) and patience you will end up with a decent product.
(in no particular order)
2" Paint brushes
9-16oz PAPER cups
1.5oz chopped strand fiberglass mat 3-5 yards
Polyester Resin [del]BP-440[/del] now 435 1 gallon
MDF Board, 3/4" thick, enough for two ~11" rings $30 for sheet, which is WAY more than you need
Fleece or old shirt or grill material, 3ftx3ft or so (craft store, or around the house) $0
Wide Masking tape $2
Aluminum Foil $2
Speaker wire, 16awg should be plenty $10
Terminals of some sort
10" Low Profile sub with low Cubic Foot requirements, fitment depends how far out you build $70-?
1 qt Bondo or Rage body filler to smooth things out $10
Wood glue $4
Mounting Screws $2
Jigsaw or Rotozip or Router for making mdf rings
Goggles for fiberglassing
Dremel for trimming fiberglass
Mat, Respirator, Resin, Gloves
Binding posts, Carpet, Grill fabric
Jigsaw, Protective eyewear, Dremel, Cut off kit, Sand paper, Bondo, Screws, Shears, Wood glue, MDF board
Paint brushes, Gloves, Protective Eyewear, Sandpaper, Bondo, Screws, Shears, Wood glue
Paint brushes, Cups, Gloves
Some notes on materials
I was recommended by an experienced fiberglasser to use www.USComposites.com
. From them I purchased
1-1/2OZ Chopped Strand Fiberglass Mat 5 yards to match with resin
1 Gallon Polyester Resin BP-440 (now called 435)
1 BINKS Respirator (Could purchase elsewhere, as long as you get a good respirator)
Other info on materials
Brushes, 2" worked the best for me and can be purchased cheap in bulk. Get the cheapest ones you can, and you need one for every layer that you put on, and they are trash after 1 use.
Sand Paper and sanding block, grits like 40-60 worked well for filler removal and general smoothing, higher grits would be needed if you choose to paint rather than carpet
Binding Posts, parts express has a lot of terminal cups but I used individual binding posts 091-1245 Dayton BPA-38G HD Binding Post Pair Gold
PAPER cups for resin mixing and application, don't get foam or plastic because resin generates heat when it begins hardening. I used 10oz cups.
MDF board, simply for the mounting rings for the sub. I bought a full sheet knowing at some point I'd make use of it, and even with changing idea's I still haven't used half a sheet. 1/4 of a sheet would be enough. I used 3/4"
You may need dowel rods and hot glue to hold up your ring if it doesn't fit the way mine did.
1) Mask off the trunk corner with masking tape
. Be sure to cover the entire corner fully, overlapping each strip a little. Put a reasonably thick layer of newspaper across the trunk to mid car, and for extra safety across the trunk lips and bumper. There is no reason to not prep properly and accidentally drip resin into your carpet or on your bumper. Unlike my picture, go entirely to the top for carpet so you can fiberglass all the way out to the edge on the top left corner of the knock out.
2) Using spray glue, attach and smooth aluminum foil across the section you intend to mold
. Excess is still time well spent if you are worried about resin penetration. Some people might skip this step but I was too concerned for the trunk liner to leave it out. I would go from the top edge where the rubber seal is, all the way around the bump in the left corner, and all the way a little past where the outer edge of the edge of the trunk is.
3) Cut up a bunch of ~3"x3" fiberglass squares.
Put on your gloves or it may itch.
4) Attach the squares to the foil using spray glue, allowing them to overlap by 1/2" to 1".
No need for extreme spray gluing, just use enough to keep each square in place while you brush the resin on. Make sure there are absolutely no gaps, and extend a little further than the edges of your intended sub box.
5) After putting on gloves and respirator and making sure that a brush and paper towels are handy, mix up a cup of resin and hardener and apply it to each square.
Mix appropriate to the instructions included with your materials. Too much hardener won't give you enough time, too little will cause it to take forever to dry, if it ever does properly. The amount you use can change with weather/humidity. It activates with heat, so colder days may require more hardener. The resin can be brushed on, but be sure to dab the squares with the tip of the brush to remove air bubbles and ensure complete saturation. Do the entire layer, even if you need to quickly grab another cup and mix up a little more resin. Don't be afraid to throw some resin away if it starts to gel up or if you have extra. I would not mix more than 10oz at a time because it would be too difficult to get it applied in time and to get the proportion of hardener/resin correct. It doesn't need to extend to the right or out on the bottom as far as I made it.
6) Allow mold to harden
. Probably 1-2 hours but I gave it a day.
IN THE MEAN TIME
Create your MDF rings[/B]. Make a circle around 1" from the outside edge of your sub. Cut it out, trace it, and then cut out the second. At that point you can trace one with an outline of the outside edge of the speaker, allowing the entire speaker to pass through the ring. The other has the same outer dimensions, but this one will allow everything but the mounting ring of the circle. If your speaker doesn't fit you can always take away more. Be sure to leave an extra 1/4" or so all the way around the larger opening so that you can fit carpet through all around the sub. I used a dremel to round the top inner edge so that the carpet would roll toward the inside easily. Use wood glue and clamps to attach the two rings together and test mount your sub to make sure everything worked, that you have the 1/4" gap, and the sub lays flat. (if new, your sub probably came with a circle for getting all the dimensions right
BACK TO THE FIBERGLASS
7) Apply more layers to the inside
. Continue using the squares method with a little overlap, giving each layer lots of time to dry. I did one layer a day, so I don't know how long is enough. I've also heard that you can do two at once, but I never bothered to try. I can't remember if I removed it from the trunk after one layer or not. I think
I did. It should be reasonably solid though, as there aren't many flat surfaces. I believe I applied 4 to the original mold. Trim up the edges to the exact spot that you prefer the face to be (remember it will get another 1/4" of extension from the face) by marking it with a sharpie and test fitting it many times to make sure you don't take off too much.
Here you can see that I failed at making the top edge. Also I hadn't trimmed it down as far as I did later, cutting off most of that right side and a lot of the bottom part
8) Insert your MDF ring, aligning it as you wish.
I angled mine in slightly toward the center of the trunk. I found that I could simply make pads with hot glue at 3 spots on the ring and make the ring level and solid. YMMV. If it doesn't work out that way for you, use dowel rods to get the right height for the ring. It doesn't need to be mountably solid, just solid enough to stretch fabric over it.
9) Stretch fabric over the ring to the edges of your mold.
I used hot glue to attach one edge firmly and then stretched it over to the other side, and then did the opposite plane. Whatever works for you. I used speaker grill cloth, but fleece works too, or I've read an old sheet or pillowcase or undershirt works. Make sure it fits 1" past the outer edges, and then use a utility knife to cut off the excess.
10) Soak fabric in resin
, as if it were fiberglass mat. You are basically creating your mold to lay fiberglass on like you used the trunk corner. No need for resin inside the ring, but be sure that it does soak firmly into the ring.
11) Lay fiberglass to the edges using the same old method, but with smaller pieces.
Because you aren't covering as much area, you don't need huge 3" squares. Cut strips or squares out and lay them out and make sure you have enough of the right shapes and sizes before you lay it. Extend them 1/2" past the edges of your mold and trim the excess later. Be sure there are NO gaps at either the ring or the edge of your previous mold. I did 4 layers onto the hardened fabric. I'm not sure if you could just cut the shape of the mold and then cut out the center without using overlaps or not. I used the overlap technique. I wouldn't bother trying to get the fiberglass to bend around the edge of the box. It didn't work for me, and made it a hassle to sand and trim. Flat past the top edge is fine.
12) Cut out the center where the sub goes
. Dremel out to the edges of the ring with a cutting wheel and a sanding drum wheel. Make the circle as round and smooth as possible, and look for imperfections
13) Trim the edges of the mold to the sides of your original mold
. Sand it and look for bubbles or gaps, and make sure the shape is correct. I put a glass of water into it and then turned the enclosure and made sure no water seeped out. Somewhat rudimentary, but allowed me to identify any problem spots and build them up with Duraglass (a short strand fiberglass filler)
14) Use Bondo, Rage, or Duraglass to fill in serious dips
. They dry in ~20 minutes enough to sand. You are going for a generally smooth surface. Carpet will hide anything minor, if you are painting it you need perfection. This may be unnecessary, but I wanted to be sure that it would be smooth in appearance and for gluing the carpet. The perfectionist in me was going to make it paintably smooth, but I got sick of sanding. I sanded with a rubber block and 40grit paper, and applied some to the edges to smooth them out a bit and round them a little for carpet.
15) Carpet your box
. I cut a square that wrapped about halfway to the back of the mold all around. Then I picked one edge (the flat bottom one) and sprayed both the mold and carpet with glue and attached it. Start working your way around the box in one direction, making sure the face stays taught. The easiest way to apply the carpet is to bunch it into a fold, cut down the line of the fold, and then glue both pieces to the back, perhaps trimming the parts that would have overlapped if it bothers you. It is a long process- I watched tv while doing it. The more time you take the better it looks. I only glued to the back of the mold to begin with until I got the whole way around. Then I cut an X in the center where the sub goes all the way to the inner ring, and pulled each flap up and shot some glue underneath to attach it to the face. Then I pulled each flap in and sprayed glue onto the top of the mounting ring and side of the upper ring and made whatever necessary cuts so that it would lay flat and into the ring. I trimmed off the excess that still stuck out, and cut a few pieces to fill the gaps where I had to allow the carpet to spread and the ring showed.
16) Attach your binding posts
(or whatever you purchased) to your box
, wherever you deem appropriate. I opted to attach mine directly to the face using gold plated everything so that I wouldn't have to cut a hole into the liner to run the wire. If you use a terminal cup, you might put it right on the back and cut that hole for the speaker wires. Your choice.
17) Wire your binding posts to the sub, mount it, and enjoy!
, I decided to put a Dynamat-like material called eDead80 throughout the inside to make the enclosure less resonant and reduce the volume slightly. Probably not necessary. I haven't done this yet, but I believe I will also have to put velcro on the back and bottom of the enclosure to keep it in place. It wants to tip if I turn hard. YMMV