This article is from the Car Audio FAQ, by Ian D. Bjorhovde (ianbjor@mobileaudio.com) with numerous contributions by others.
What you will need:
* Adhesive (3M Super 77 or Super 90 is excellent.)
* Carpet.
* A good sharp pair of scissors.
* A razor sharp utility knife. Buy a BOX of blades, they go dull
fast.
* Solvent to clean up excess adhesive.
Before you start, find a large, clean, flat surface on which to set the
box as you carpet it. Start by unrolling the carpet onto the surface,
smoothing it out so that its flat, and setting the box on top of it
edgewise. Also, make sure that you remove the speaker, any ports and
terminal cups from the box.
The instructions on how to carpet the box are as follows:
1. Place the box such that it is centered on the carpet lengthwise,
and one edge of the box is about one inch from the edge of the
carpet.
2. Roll the box back so that the side of the box that was previously
done faces forward, and the carpet beneath it is exposed. Coat
both the box and carpet with adhesive, but do NOT apply the carpet
to the box - the adhesive needs a few minutes to set up (follow
the instructions from your adhesive to find out how long you
should wait).
3. After the adhesive has set up, roll the box back into position.
Wait a few more minutes for the adhesive to bond.
4. Now coat the side of the box adjacent to the remaining carpet (the
side facing backwards) and the carpet next to it with adhesive,
let the adhesive set up, and roll the side you just coated onto
the coated carpet. Repeat this until three sides of the box are
carpeted.
5. Before carpeting the next side, the 1 inch of carpet sticking over
the edge must be removed. To do this, rotate the box so that the
first side that was carpeted is up. Pull the carpet sticking over
the edge down towards the uncarpeted edge and cut it off with the
knife, flush with the uncarpeted side of the box. You will have to
run the knife nearly parallel to the uncarpeted side to get a
perfect cut.
6. This done, spray the remaining side and carpet, and roll the box
onto it. Shear off the remaining carpet sticking out from all
edges with the scissors leaving a 1 inch border everywhere.
7. Clean up the ends of the box so that the carpet is flush with the
sides of the box as in step 4.
8. Next cut off the remaining 1 inch flap of carpet (located at the
point where you began carpeting). This is the tricky part, as you
don't want to be able to see this seam. Again, pull the flap down
over the edge of the box, but this time cut it at roughly a 45
degree angle. If you are successful you shouldn't be able to see
the wood under the seam, but will probably see the white of the
adhesive and the back of the carpet.
9. Soak some of the solvent onto a rag and use this to scrub the edge
you just cut off. It should dissolve the adhesive and the carpet
backing somewhat, causing the carpet on the edge to become fuzzy.
Keep scrubbing the edge until you can no longer see the seam.
10. Now carpet the ends of the box. Cut two pieces of carpet slightly
larger than the ends of the box and lay one of them flat on the
surface. Spray the carpet and one end of the box with adhesive,
and set the end of the box on the carpet, so the box stands on end.
11. After the adhesive has dried sufficiently cut off the remaining
border of the carpet as in 7 and 8.
12. Repeat step 9 and 10 for the other end of the box.
Congratulations! You've just carpeted your box!
 
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