Draw a line across the center of the 13-inch board so it is parallel with the 13-inch edges and 1 inch away from those edges. Draw five lines perpendicularly across the first line. Space them 2.5 inches apart, leaving the two outside lines1/4 inch away from the ends of the board.
Drill a 3/8-inch hole through the board where each of the lines intersect. Turn the board over so the holes are parallel with the floor and repeat the first step. Drill five more holes halfway through the board. These holes should connect perpendicularly with the first set of holes drilled.
Insert five dowels through the first set of holes that were drilled. The dowels should be centered with each end 2 inches away from the board. Place a dab of glue through the second set of holes and rotate the dowels to spread the glue around inside the holes.
Place another dab of glue inside each of the five open holes. Insert the last set of dowels into these holes. Let the glue dry according to the glue bottle's instructions.
Position the 13-inch board on the 6-inch board so it is centered with the sides parallel. The sides of the 13-inch board should each be 4 inches away from the edges of the 6-inch board. Drill two 3/32-inch holes through the 6-inch board and into the 13-inch board. These are pilot holes. Drill a 1/4-inch deep 3/32-inch hole into each pilot hole and screw the boards together.
Sand down your sunglass rack with medium-grade and fine-grade sandpaper. Wipe it down using your tack cloth and apply wood stain. Let the rack dry.
Place your sunglasses on the rack. Rest the temples on the dowels that extend 2 inches away from the 13-inch board, and so the bridge rests on the dowels that extend 5 inches away from the 13-inch board.