The Sand Machine Part 2

Considering some significant limitations, it was possible to simplify the material cutting using a modular building (see Figure 10-1). By adopting a magnet to move the iron sphere to draw on the sand, the bottom side of the box should be relatively thin. After several experiments, I found the most reliable compromise: an iron ball with a 10mm diameter can move easily over a few millimeters of sand, supported by the bottom surface made with plywood that's 3mm thick. See Figure 10-2.