Carpeting is an easy and relatively cheap way to improve the appearance of your plywood subwoofer housing. It makes the housing feel more integrated into your car, and also protects the wood and softens the sharp edges of the box. While most custom automotive audio shops will offer this service, you can carpet the box yourself much more cost efficiently.
Purchase box carpeting in the color of your choosing. Box carpeting is thinner and more flexible than other kinds of carpeting, which makes it easier to use and fold over edges. Cut a piece of carpeting long enough to wrap around the bottom, front, top, and back of the box with a couple inches of overlap on the bottom and enough overhang to cover the sides when folded over itself.
Apply contact adhesive to the bottom, front, top and back of the box and to the carpet. Wrap the bottom, front, top and back of the box, beginning midway through the bottom of the box. Make sure the carpet is taut and smooth throughout this process.
Fold the excess carpet over the spot on the bottom where you started. Find the relative middle of the overlap area, and using the razor blade, cut all the way through both layers of carpet at once. This will ensure that the carpet lines up exactly without any gaps. Press the two ends together and smooth the carpet, pushing it towards the seam.
For the sides, slice the overhanging carpet starting at each corner and moving outwards in a straight line to create four flaps. Set the box bottom down, and apply contact adhesive to the sides and to the flaps of carpet. Fold the top flap down and trim so that there is no overhang on the sides, then do the same with the bottom, allowing the bottom to overlap the top. Again, slice the carpet as done on the bottom, so that the two flaps form a perfect seam.
Fold one side flap inward, laying it over the top and bottom flaps already pressed to the box. Start at one corner of the side flap and cut a small arc, or crescent moon shape, to the other corner of the flap, slicing through both the side flap and the top and bottom flaps already pressed down. Lift side flap and remove the sections cut from top and bottom flaps, and then press the side flap onto the box, aligning its edge with the crescent edge created in the top and bottom flaps. Press down and smooth out carpet, pushing carpet toward the seam.
Repeat on other flap. Then repeat entire process on other side. When finished, fluff the carpet to further hide the seams.
Find the speaker and outlet holes. Starting from the center of the hole, cut a line across the hole. Trim carpet until there is just enough to fold over the edges of hole, about an inch. Apply adhesive around the edge of the whole on the inside of the box and on the back of the carpet. Fold over the edges of the hole and smooth.
