Things You'll Need
Instructions
Level the spot in your yard where you will be placing the sandbox.
Cut one of the 2-by-8-inch-by-8-foot pieces of treated wood in half. Using the two halves and the other two 2-by-8-inch-by-8-foot pieces, lay out a rectangle with the 2-inch sides facing up. Screw together the 4-by-8-foot rectangle with 4-inch screws, three in each corner.
Lay out the 4-by-8-foot piece of plywood on top of the 4-by-8-foot rectangular frame. Attach the plywood to the frame using 2-inch screws, about one screw every 6 inches. Flip the box over so that the plywood is on the ground.
Cut the 1-by-8-inch-by-8-foot piece of wood in half. Attach each 4-foot half to opposite 4-foot sides of the top edge of the sandbox using 2-inch screws (about 6 inches apart). This will serve as a little bench to sit on, as well as keeping the sand inside the box.
Add sand. Make sure to get coarse sand, as fine sand's dust particles are harmful to kids' lungs.