Lay out four 1-by-6-by-48-inch hardwood boards on the working surface with their best sides facing down and their long, thin sides touching. Position three 1/2-by-4-by-22-inch boards across these boards, perpendicular with their large surfaces touching. Space the boards evenly.
Spread a bead of caulking between each of the long boards and press them together tightly. Wipe of any excess caulking. Drill two holes down through the thinner boards and into the larger, wider boards. Attach the boards together with 1-inch wood screws, drilling the screws into place until the heads of the screw were flush with the surface of the board. Let the caulking dry for three hours or more.
Flip the counter upside down. Sand the edges of the counter with medium-grit sandpaper until the edges were rounded and smooth and the corners are no longer sharp. Sand the entire surface of the counter with fine-grit sandpaper to prepare it for stain or paint. Wipe down the entire counter.
Apply the first coat of paint or stain in long, smooth strokes across the surface of the counter. Let it dry for three hours and reapply additional coats with the same method. Apply waterproof sealant following the same method. Let the counter dry overnight.
Set the completed countertop on the beach bar and drill holes up through the frame of the bar and into the countertop. Space the holes every 12 inches. Apply a layer of glue between the countertop and the frame if desired. Screw 1-inch wood screws up through the frame and into the countertop, being very careful not to break through the top surface of the countertop.