Cut two pieces of 5/4-inch by 4-inch board to a length of 80 inches each, and measure and mark a line 3/4 inch from the bottom of each board. Cut two pieces of 1-inch-by-10-inch board to the same length. Nail the first piece of 5/4-inch-by-4-inch board to the 1-inch-by-10-inch board, on the pencil line. Repeat with the second piece. These are the side pieces of the bed.
Cut two pieces of 1-inch-by-10-inch board to a length of 61 1/2 inches. These are the head board and foot board. Nail the head board and foot board to the side boards, ensuring you mount the 80-inch boards inside the 61 1/2-inch boards. The dimensions on the inside of the bed should now measure 60 inches by 80 inches. Use a 90-degree square to ensure the frame is square.
Cut two pieces of 1-inch-by-4-inch board to a length of 60 inches each. Turn the frame upside down and nail one piece of board to the frame near the head of the bed and the other at the foot end, to support the frame. Cut two pieces of 1-inch-by-3-inch board to a length of 60 inches, position them evenly in between the 1-inch-by-4-inch supports and nail in place.
Turn the bed the right side up. Cut a piece of 2-inch-by-4-inch board to 80 inches. Cut two pieces of 5/4-inch-by-4-inch boards to 80 inches. Nail the two 5/4-inch-by-4-inch boards to the sides of the 2-inch-by-4-inch board, creating a U shape. Position this U-shaped beam lengthways in the center of the frame, and screw into the foot board and head board.
Screw a heavy-duty top plate, available form hardware stores, to the bottom of the frame in each corner. Screw the legs into the plates.
Cut 14 1-inch-by-3-inch boards to a length of 60 inches, space them evenly across the bed frame and screw in place.
Cover the frame with a foam mattress cover, stapling it into place on the inside of the frame. Repeat the process with a fabric of your choice.