Lay out two 24-inch 2-by-4 boards with their larger surfaces on the ground, parallel to each other and 17 inches apart. Put two more of these boards on top of them, perpendicular so they make a square frame, 24 inches to the side. Drill two holes in each corner and then attach the boards together by drilling 2 1/2-inch wood screws in each hole. Repeat to build another square wood frame.
Stand the two wood frames, which are the leg supports, upright and space them 2 feet from each other and parallel. Lay out six 36-inch 2-by-4s across the two leg supports, evenly spaced front to back and side to side. Keep the front and rear 2-by-4 even with the outside surfaces of the leg supports. Drill two holes through each long board, or seat board, and into each leg support. Attach them together with 2 1/2-inch wood screws. Repeat all previous work to create another bench.
Position a 3/4-by-36-by-36-inch sheet of plywood vertically behind each bench. Have an assistant hold them in place and drill 2 1/2-inch wood screws through the back of the plywood and into the seat boards and the leg supports, spacing the screws every 12 inches.
Set the benches on their sides, facing each other. Suspend two 60-inch 2-by-4s against the leg supports of the benches. Slide the benches back to the edge of the long board. Screw the long boards to the benches by drilling four screws through the long board and into each leg support.
Position two 36-inch 2-by-4 boards with their small ends against a long board directly between the benches, spaced about 8 inches apart. Hold the boards parallel to each other with the help of an assistant, so that their edges are even with the edges of the long board, but they are perpendicular. These will be the supports of the table. Drill two holes through the long board into the end of each table support. Attach with 2 1/2-inch wood screws. Repeat to add two identical boards on the other long board.
Set a 3/4-by-24-by-36-inch plywood board evenly on top of the four table supports. Drill two holes down through the plywood into each table support. Attach in place using 2 1/2-inch wood screws.