Measure your box to see how much box carpet you will need to use. You want one piece for the entire back, bottom and front of the box and two large separate pieces for the remaining sides. Many boxes are designed with protruding edges that make it easier to wrap the carpeting completely around each box.
Cut the first large piece of carpet, leaving enough on the sides to wrap around the protruding edges of the speaker box. Spray the carpet with adhesive and apply the carpet around the edges, cutting any excess with your razor knife. Start the carpet on the bottom, where you will also end the carpet, reducing the visibility of the seam.
Cut holes for the speakers, leaving about one half inch extra to wrap to the inside of the box and glue. One simple way to do this is cut out a star pattern in the carpet where each speaker hole will be and fold the points around the inner edge and secure with adhesive on the inside of the box.
Cut two oversized pieces for the sides and spray with adhesive. Place the two pieces and cut off excess with razor knife.