Right Angle Braces – Wood Mag Tip of the Day For each pair, start with a 12″ square of 3⁄4″ Baltic-birch plywood and cut it in half diagonally. Then cut notches for the clamps, above. You can vary sizes to suit larger or smaller projects. The braces help with more than glue-ups. Clamp a pair to a chest, above, to support the lid as you install hinges.