Figure out the dimensions you want for your batting board and write them down.
Cut your foam board to the dimensions for your board using an exacto knife. If it is not large enough for your desired dimensions, you may need to use multiple foam boards and tape them together with duct tape.
Cut batting and fabric to match the dimensions of your board, adding three inches to both the length and height.
Cover the front of your foam board with batting, folding it over the board's back edges around its entire perimeter. Secure with duct tape at the back edges.
Use your saw to cut a 1/2-inch thick sheet of plywood in the dimensions of your board dimensions.
Put your foam batting padding on one side of the wood, using spray adhesive to secure it in place.
Cover the padded side with another layer of batting with fabric on top of the batting. Pull each edge of the batting and fabric to the back edges of the wood board and use a staple gun to secure to the wood.