Assemble the base of the frame by laying the 17 1/2-inch by 83 1/2-inch section of plywood on a flat surface. Apply wood glue to the 83 1/2-inch edges. Line up the corners and gently press on 24-inch by 83 1/2-inch section of plywood in standing position on each side to form a U-shaped frame. Apply wood glue around the top and bottom edges of all three wood sections and press one 18-inch by 24-inch on each end.
Screw the 18-inch by 24-inch sections to the U-shaped structure by inserting a screw every 4 inches around the outer perimeter.
Screw the two 24-inch by 83 1/2-inch sections of plywood to the 17 1/2-inch by 83 1/2-inch section by inserting a screw every 4 inches along the glued edges of the plywood.
Screw in four shelving brackets every 14 inches from the base of the cabinet. Place one shelving bracket for each corner of the shelf. Stand up the cabinet and slide the shelves into place.
Measure in 6 inches from each corner of the 18-inch by 84-inch section of plywood along the 84-inch edge. Attach hinges at these locations. Line the 18-inch by 84-inch door section to the front of the cabinet and attach the hinges to the cabinet.