Mark two long rear panels on one sheet of particle board. Measure one panel to be 8 feet by 17 inches and the other panel to be 8 feet by 17 1/2 inches. Use a chalk line to mark the measurements.
Mark two triangular end caps in the unused area of the particle board. Make each end cap a 45-45-90-degree triangle with sides 18 inches, 18 inches and 22 1/2 inches. Use a pencil and straight edge.
Cut the two long rear panels and the two triangular end caps with a circular saw.
Build the back of the first corner trap with a 90-degree butt joint. Use drywall screws and wood glue to attach the long edge of the 8-foot-by-17-inch piece to the long edge of the 8-foot-by-17 1/2-inch piece. Place the 1/2-inch edge of the 17-inch wide piece against the 17 1/2-inch side of the slightly wider piece so that the inside dimensions of the assembled corner are both 17 inches.
Attach the triangular end caps to the tops and bottoms of the back section you just built. Use wood glue and drywall screws.
Lay the wood box down on its back.
Fill the box with semi-rigid fiberglass insulation to within 1 inch of the front opening.
Trim the long edges of two acoustic ceiling tiles to a clean, 45-degree bevel. Trim them with a straight edge and utility knife so that the fronts remain 2 feet wide and the backs are narrowed to about 22 1/2 inches.
Staple the acoustic ceiling tiles flush to the front opening of the enclosure, leaving the factory-finished side facing out.
Place the finished acoustic ceiling tile bass trap upright in one of the rear corners of your control room.