To build a work table on wheels, first cut eight 1-by-6-inch wood boards to 3-foot lengths to use as vertical supports. Secure two boards into a right angle and the length of each board. To prevent splitting, pre-drill the holes for 3-inch wood screws. Repeat to make four 3-foot corner panels.
Cut four 2-by-4-inch boards to 8 feet to make the crossbars that fit between the corner panels, making the side of the table. Place two panels 8 feet apart and parallel to each other and attach two crossbars perpendicular to the panels using 3-inch wood screws. Place one crossbar about a 1/2 inch from the top corner of the panel and the second about 6 inches above the bottom of the panels. Repeat this process with the other two corner panels.
Next, cut four 2-by-4-inch boards to 45 inches to create the end crossbars that fit between the two side sections of the table. Secure each end crossbar at the same height as the side crossbars using 3-inch wood screws. The end result is a rectangular table frame.
Place the frame upside down and secure locking casters at each bottom corner of the table, using screws or caster brackets. Turn the table back upright and lock the casters to prevent the frame from rolling. Place 3/4-inch thick 4-by-8-foot plywood sheets onto the crossbars between the supports. Trim any excess edges so the top of the table fits correctly into the corner panels. Use 3-inch wood screws to secure the sheets.