We confirmed the presence of stiffness anisotropy, which is one of the typical properties of the corrugated structure, by conducting a three-point bending test in two directions (x and and y), as shown in Figure 8c. Given that the tension and compression testing machine (Shimadzu, AG-50kNX) did not allow the installation of wooden plates in the y-direction, we used a desktop type tension and compression testing machine (A&D, MCT-1150) for the y-direction compression. Figure 8d presents the load-deflection curves obtained from the three-point bending tests conducted in both directions. The results reveal that the stiffness was high in the x-direction and low in the y-direction, which is a typical property of the corrugated structure.