With a size of 8 x 8 x 5.5 mm and a 0.2 mm step size, this motor is the smallest 3-D printable pneumatic stepper motor. The cylinder cross-section is only 2.5 mm square. Print a few spare pistons, if you drop one on the floor then you may not be able to find it back.
It is essential to print it in the highest possible resolution, in order to make the triangular teeth as sharp as possible. If you get sine-wave shaped teeth instead then it may not work.
Cut seals sized 2.6 x 2.6 mm from 0.5 mm silicone rubber. Experiment with best settings until you get a good tradeoff (low friction and low leakage).
When printing with a Polyjet printer (e.g. Objet260 Connex3), use glossy print mode to make cylinder walls as smooth as possible.