I once lived in Finland for a year. It was really dark during the polar night, and I didn't feel like going out, so I spent most of my days off inside the house working on my computer. I was wondering if I could make a tool to stimulate the soles of my feet on the floor, and while I was making sketches, an interesting shape appeared. I found the shape as a chesnut. Then I actually carved out a white birch and made a foot acupressure pad that fit perfectly. After returning to Japan, I have been making it with various materials, however, I feel most comfortable with the one made of wood.