2x6x10 pine boards will be cut once at 7 feet, leaving a 3-foot section to be used for the sides.
2x6x12 pine boards will be cut twice. One cut at 7 feet and another at 3 foot, leaving a 2 foot piece to be used as bracing in the center.
Cut the 4x4 pine board into four sections, 2-feet each.
The 7-foot pieces (2x6 boards) should be lined up to be flush with the ends of the 3-foot (2x6 boards). Predrill and countersink holes and use 3 ½-inch screws to secure boards together on all four corners.
Measure the rectangle to make sure it is square. Then place 4x4 (2-foot) boards in each corner. Predrill and countersink holes and use 3 ½-inch screws to secure boards on all eight sides, contacting the 2x6 boards. (Approximately 3 screws per side)
Continue placing 2x6 boards and fastening at each end in the same manner as the same boards, until all boards are fully secured.
Take the 2x6 (2-foot boards) and place them vertically in the center of the 7-foot section, spanning all four 2x6 (7-foot boards) on each side. Predrill and countersink and use the 2 ½-inch screws to secure. (Approximately 2 screws per 7-foot long board)