Use medium density fiberboard to construct a subwoofer box's main cabinet. The extra materials that are necessary include screws, carpenter's glue, caulk and a speaker terminal cup. After constructing the box, you can cover it with carpet as an optional extra.
Make a note of the manufacturer's recommended enclosure size when purchasing the subwoofer. The subwoofer performs at its best when the box is the optimum volume.
A cube is the simplest box to build, however if the subwoofer is for a car, building a wedge-shaped box may help it fit into the trunk. The box's interior dimensions determine its volume, but you should use the exterior dimensions, which include the fiberboard's thickness, when assessing the space in the trunk.
A hardware store can cut the fiberboard into pieces; otherwise a table saw is the best option for achieving straight cuts that seal well. Use a compass or template to mark the cutout for the speaker, and cut the hole out using a jigsaw. It is best to use double thickness fiberboard for the speaker panel, as the speaker generates air pressure inside the box.
Cut a rectangular hole in the back panel using the jigsaw, and install the terminal cup. The box is now ready for construction; use liberal amounts of carpenter's glue, along with drywall screws, to hold it together.
Drop the speaker cone into the hole to ensure it fits, then remove it and run silicon caulk around the interior seams. Secure the speaker to the box with rope caulk and screws.
Customize the box further with a carpet or vinyl covering, or add interior lighting and a transparent Plexiglass panel to display the speaker.