Determine the dimensions of the table top. For this mitered tabletop design, saw the 4-by-8-by-96-inch lumber into two boards measuring the desired width of the table and two measuring the desired length.
Saw the ends of each board off from one corner, at 45-degrees, so that two pieces fit together in a right angle. This is the mitering. When all the boards are connected in this way, there will be a hole in the middle of the table. Measure the dimensions of this hole and cut 2-by-4-inch lumber to fit within the hole.
Glue the outside boards of the tabletop together at their ends.
Place the 2-by-4-inch center pieces into the hole, leaving 1/2 inch of space above them. On the underside of the table, secure them each into the table, using a corner bracket and 1-inch screws on each side.
Coat the top of the boards, inside of the tabletop, with a strong wood adhesive. Cut and hammer into place a half-sanded plywood sheet so that the table top is even and smooth.