Saw four 2-by-10-by-96-inch lumber boards into 2 side rails that measure 80 inches in length and 2 end rails that measure 81 inches in length.
Cut five 4-by-10-by-96-inch lumber planks into 6 legs that measure 66 inches in height.
Cut one 2-by-4-by-96-inch lumber board into a center support beam that measures 77 inches long, and two 2-by-2-by-96-inch planks into two slat support rails that measure the same.
Divide eight 1-by-6-by-96-inch lumber boards into seven 81-inch slats and 4 ladder rungs that measure 28-1/8 inches long.
Build a rectangular bed frame by butting the end rails perpendicular to the side rails and ensure that they are flush with the ends of the side rails. Secure each joint with six 3-inch screws that you countersink into the wood.
Measure 3 inches down from the top of the frame and screw the slat support rails in place with 3-inch screws placed every 12 inches. Turn the frame over.
Lay the slats atop the supports and glue them into place using wood glue.
Cut 1-1/2 inch ledges out of the tops of each leg, going down about 9.25 inches so that the cutout is equal in dimension to the frame rails.
Rest the bed frame atop the ledges cut into the legs, so that there are three legs on either side of the bed, and drill a 5/8-inch hole through the frame and each leg. Put a 4-inch bolt though each hole and secure with a nut.
Screw the ladder rungs, flat side facing out, between any two legs using 3-inch screws and wood glue.