Prepare two wooden strips, one long and one short. It is best to have a golden ratio of about 1:1.6. Find the midpoint of the short wooden strip to make a mark. Measure half of the length of the short strip and mark it on the long strip of wood. In the first step, apply latex to the vicinity of the two mark points and fold the two mark points together. In the second step, the two mark points are coincident, nailed to the mark point, and then fixed by a few nails. In the third step, the width of the wooden strip is measured at a right angle of 90 degrees along the two wooden strip marking points, and the depth is half of the wooden strip. Then, the two wooden strips are combined by cross, and the troughs are exactly matched, glued together with latex, or nailed up.