The Family Handyman
Round toothpicks work great for locking the mitered corners of picture frames. When each corner is cut and glued, drill pilot holes (the same diameter as the toothpick) from each side of the corner. Apply glue to the toothpick and tap it into the hole. When the glue sets, cut the excess toothpick flush with the frame, and then stain or paint it to match for a nearly invisible fastening job.