Cut four scrap pieces of wood to be 20-inches long and two pieces to be 60-inches long.
Create the top part of the frame. It has to support the top of the bench, as well as any items placed on the table. Place the 60-inch pieces of wood on the floor parallel to each other, leaving about 20 inches between them.
Place the four 20-inch pieces perpendicular to, and between, the two 60-inch pieces. Put one at each end of the longer pieces, and the other two 20-inch pieces 16 1/2 inches from the two end pieces. Screw each of the 20-inch pieces onto the 60-inch pieces. This rectangle is the frame.
Secure the OSB on top of the frame with screws every 5 inches until it is secured completely on all four sides. Drive nails through the two center pieces of the frame as well.
Attach the four wooden posts to the top of the structure in each corner. They will be its legs. Drive nails through the top of the OSB sheet and into the legs.
Sand the entire work bench to get rid of any rough edges or splintering pieces.