Place the 24x70x¾-inch plywood on a worktable. Cut the veneer strip into four pieces; two at 72 inches, two at 26 inches. Place one of the 26-inch strips on one of the 24-inch edges.
Heat the strip with a hot iron to activate the glue on the back of the strip. Work your way up and down the strip slowly; the goal is to get a good bond to the edge of the plywood.
Once it has cooled, fold the excess over the corner of the plywood to get an even break. Repeat this process on the other three edges. Knock the excess off the top and bottom edges with a sanding block. For more on how to apply iron-on edging, check out "Installing Iron-on Edging" in the resources below.
Measure and make marks at 2 inches and 21 inches from the 24-inch edges. Place the framing square on the marks and draw lines across the grain. This indicates where the filing cabinets will secure to the plywood top.
Remove the drawers from the two cabinets, turn them upside down and place them on the lines to ensure they fit within them. They will be flush with the front edge of the top. Make any adjustment necessary, then remove them and apply glue to the area where they will be installed. Place the cabinets on top of the glue and secure them with the drywall screws. Clean excess glue with a damp cloth.
Next, install the keyboard tray according to the manufacturer's instructions. Set the desk upright to check its height. If it is too low for you, go to the next step.
Draw a line 1 inch from the edge around the perimeter of the bottom of the cabinets. Next, draw the pattern of the leg in the corners of the lines. For example, if the leg is 3 inches square, then draw a 3-inch square. Mark the center of the square and drill a pilot hole with the 1/16-inch drill bit for the legs and screw them in place.