Use a straight edge to draw a two lines on each 60-inch sheet of plywood. The lines should run along the 60-inch side and each line should be 12 inches from one edge of the plywood.
Drill pilot holes in the 60-inch plywood sheets using a drill bit 1/8-inch narrower than the diameter of your wood screws. Drill holes along each of the lines at 10, 20, 40 and 50 inches from one 24-inch edge.
Drill two pilot holes in each end of all 40-inch plywood sheets. Use the same drill bit you did for step 2, positioning the holes on center and each 12 inches from one edge of the end.
Drill a two-inch diameter hole in the center of the composite board. If you plan on keeping a gaming console, DVD player, DVR recorder or other devices on these shelves, drill additional holes at 6, 16, 46 and 56 inches from the end to pass cords through when you install the electronics.
Assemble a rectangle using both 60-inch plywood sheets and two 40-inch plywood sheets. Screw them together by driving wood screws through the pilot holes in the large sheets and into the pilot holes in the ends of the smaller sheets.
Add additional shelves by sliding the other 40-inch shelves in parallel to the first two. Screw them in by driving screws through the pilot holes as you did in Step 5.
Lay the composite board on top of the frame with its edges flush with the edges of the frame. Nail it in place with one finishing nail per corner. Reinforce with two evenly spaced nails for each short side and three evenly spaced nails for each long side.