Place the two 3/4-by-8-by-48 inch panels parallel to each other on a work surface. The 3/4-by-48 inch edges should be flat on the work surface. Space the inside edges of the panels 46-1/2 inches apart.
Position the two 3/4-by-8-by-46-1/2 inch panels between the 3/4-by-8-by-48 inch panels to form a square box.
Drive four evenly spaced wood screws through the 3/4-by-8-by-48 inch panels into the ends of the 3/4-by-8-by-46-1/2 inch panels to secure the box assembly together using a screw gun.
Center the 3/4-by-48-by-48 inch plywood panel over the box assembly and lay it flat. Drive wood screws every 4 to 6 inches through the panel into the edges of the box assembly with a screw gun. This is the bottom of the drawer.
Position one caster in each corner of the drawer bottom. Drive the included screws through the mounting holes in the casters into the drawer bottom with a screw gun to fasten them in place. Turn the drawer assembly upright so that it rests on the casters.
Select one side of the assembly to be the front of the drawer. Center a drawer handle on the front side and fasten it with the included screws and a screw gun.