Cut the door to the dimensions of 72 inches by 29 inches. A door with different dimensions will require some adjustments to the measurements and construction of the table.
Cut three support pieces for the table top to a length of 26 inches out of a 2-by-4 plank. Screw one support in the center of the bottom side of the door across the short dimension. Screw one support on each end of the door about 6 inches from the end. Line the supports up with the thicker parts of the door so the screws do not show through to the top side.
Cut four legs to a length of 30 inches out of 2-by-8 planks. Cut both ends of the legs to a mitered 20-degree-angle so the ends set flat on the ground and flush with the table top when set at an angle. Cut two cross-support beams out of 2-by-8 planks to a length of 60 inches. Trim the corners off at a length of about 1 inch to shape the ends and eliminate the sharp point.
Flip the door top so the right side is facing down and the support brackets are facing upward. Attach two legs to each end support with deck screws so the legs are flush with the end of the bracket and angled outward to create an “A” shape. Measure 15 inches from the bottom of the leg and attach the cross support beam to each set of legs with carriage bolts. The beam overhang supports the seat.
Cut two 40-inch lengths from a 2-by-4 plank, and miter the ends to a 45-degree-angle. Attach one end to the center-support attached to the table and the other end to the cross-support beam with deck screws. Turn the table upright.
Cut four 72-inch-long 2-by-6 planks for the seat. Attach two planks on each side of the table to the cross-support beam overhang. Use two deck screws on the end of each plank to secure the bench in place.
Sand the surface and edges of the table. Apply and outdoor paint or stain, if desired. Seal the door table top with an outdoor acrylic sealer to make it weather-proof.