Cut the Wood
Use a piece of 1/2-inch-thick or 5/8-inch-thick plywood to cut a board about one foot wide and two feet long. Decide how many holes your board will have, and determine whether you want the holes to be round, square or another shape. Mark the holes and cut a starting point with a drill, then use a jigsaw to cut along the outline of the shapes. The holes should be 4 to 5 inches in diameter.
Attach the Support
Some bean bag board designs are rather elaborate, with side panels and extra support. However, your bean bag board only needs one supporting board or leg to prop it up. Because your bean bag board is 12 inches wide, cut a 12-inch by 12-inch supporting piece of plywood. If placed at the very top of the board, it will raise it 12 inches from the floor. For a higher angle, move the support board closer to the center, about halfway between the top and the center.
Cut a 12-inch-long piece of a 2-inch by 4-inch wood stud, and attach it widthwise across the back of the board, either 1/2 or 5/8 inch from the top, or halfway between the top and the center. The extra 1/2 or 5/8 inch is to allow the 12-inch by 12-inch wood piece to neatly fit under the top of the bean bag board. Put wood glue at the location of the wood stud, and use 2 1/4 wood screws to screw the wood stud piece to the underside of the board.
Put wood glue on the top side of the wood stud, then position the support board perpendicularly to the back of the bean bag board. Screw the support board into the wood stud.
Decorate and Varnish
Allow the wood glue time to dry, and then sand the entire bean bag board. Sand away the sharp corners to prevent injury. Decide whether you want a natural wood look for your game board, or if you want to paint it and decorate it with fun and brilliant designs. Apply a coat of varnish or polyurethane to protect your board for many years to come.
Make Bean Bags
Make your own bean bags as you wait for the board to dry. Purchase fabrics or use fabric remnants and scraps to make bean bags in any color or pattern you like.
Simply cut 4-inch by 4-inch squares, two pieces at a time. With right sides together, sew the outside edges of the bags together, leaving an opening on one side. Turn the bean bag inside out and fill with small dried beans or peas. You can also purchase polystyrene bean bag filler, or use buckwheat hull or wood chips.
Fill your bags, then sew them closed. Sew several bags so that many people can play at one time without collecting the bags after each turn.