Measure the length and width of the bar using the measuring tape.
Adding 4 inches to each of the measurements -- the length and width -- determines the dimensions for your patio bar top with appropriate overhang.
Measure the dimensions on the plywood and mark them using a pencil.
Place the plywood on a sawhorse and cut it with a circular saw to the dimensions that you marked.
Place the top on the bar and secure it into the base using 2-inch wood screws. Insert a minimum of one screw every 6 inches, using the drill.
Cover the top of the bar with the beach mats and staple them into place with the staple gun.