Attach the Table Legs
Turn the lower surface upside down and attach four wooden blocks (2" x 4" x 4") near the four corners. These blocks can be regular 2" x 4" scrap wood or leftover true-cut 2" x 4" reclaimed wood. Screw them to the underside of the lower surface.
Using old 4" x 4" posts, cut four legs to length depending on the desired surface height of the tabletop. The legs must be of equal length and cut clean for a plumb and square fit.
Turn the checkerboard surface face-down and lay it on the work table. Place the four post legs in each of the four corners. Using the finish nailer, secure the legs through the side edge trim. Also, toenail the legs to the underside of the checkerboard, judging carefully how deep the finish nail will penetrate without going all the way through to the checkerboard surface. Take the bottom table surface and turn it face-down. Place it upside down on the four legs. The bottom table surface should be adjusted so the legs are aligned with the corners inside the edge trim. With the legs in place, finish nail through the bottom of the table to temporarily hold it in place. Insert four wood screws per leg through the bottom to permanently secure the legs in place.
Carefully turn the table right side up.