Cut 8 pieces 36 inches long from the 2-by-4 lumber. Cut 4 pieces 3 ½ inches long. Apply wood glue to 2 of the edges of the block and secure it to 1 end of 2 of the 36-inch pieces with the drywall screws. Be certain to lay the block flat when it is secured to the 36-inch pieces.
Cut 4 pieces 12 inches long. Apply wood glue to 1 of the 3 ½-inch sides and place it at the bottom of the legs. Secure it to both legs of the workstation with the drywall screws. If another shelf is desired, cut 4 more 12-inch pieces and place them half the distance up from those that were just secured to the legs.
Cut 1 (2 with a middle shelf) piece(s) of plywood to 21-by-48 inches. Cut 2 side rails from the 1-by-2 to 48 inches in length. Cut 2 pieces 19 ½ inches long. Secure the 48-inch pieces to the bottom (and middle) shelf with the drywall screws.
Cut another piece of plywood for the top. It needs to be 26-by-54 inches. Cut and secure 1-by-2s to 3 sides of this shelf. The open side of the top shelf is the front of the bench workstations.
Apply wood glue to the tops of the 12-inch pieces. Secure the bottom shelves with the drywall screws. Repeat this for the top shelf. Next, apply glue to the tops of the legs. Secure the 26-by-54-inch plywood to the top of the workbench with the drywall screws. This piece will hang over the bench 1 inch all the way around the top of the workstation. For alternative ways to attach the legs to the top, see "Building a Table" in the Resource section of this article.