Gluing a miter joint together often requires a special clamp. Don't have one? Well, here's how to make a clamping jig that will do quite nicely. Using a combination square, lay out a right triangle on a scrap piece of three-quarter-inch plywood. Cut out the shape using a bandsaw or jigsaw. Save both pieces. Put one on the outside of the joint, the other on the inside. Squeeze together with a C-clamp and voila, the joint will be tight and square.