At first glance, the machine looks almost underwhelming. Inside a brightly lit laboratory at On’s Zurich headquarters, a robotic arm rotates a plastic model of a human foot. At the same time, a nozzle continuously sprays 1.5 km (0.93 miles) of thin molten plastic with almost hypnotic precision.
Layer by layer, the filament wraps itself around the foot mold, gradually forming the upper of a running shoe. The entire process takes about three minutes.
