We’ve been asked several times over the last few months how sub boxes are built, and lucky for us, the crew at Superior Auto Sound, in Phoenix, Arizona, snapped plenty of photos while they built the enclosure for Steve Burkett’s Yukon. Follow along to see how a few sheets of MDF (medium density fiberboard), body filler, fiberglass, and fabric were transformed into a flowing enclosure that houses four Kicker L7 12-inch subwoofers.