A laser-cut pneumatic piston was created by cleverly using sliding-holes valves. When the valve is in one state, it directs air to one end of the piston-chamber, causing the piston to move towards the other end. The movement of the piston in turn makes the valve slide, so that once the piston has reached the end of its stroke, the valve has entered a new state, causing air to be directed to the other end of the chamber. This causes the piston to go in and out repeatedly.
To cleverly avoid the valve moving before the piston has completely reached its alternate state, this project uses a gap mechanism that prevents movement before a certain point.