Additional materials and tools
Silicone rubber sheet, 1mm thick
4mm (outer diameter) pneumatic tubes, e.g. polyurethane tubes or Lego pneumatic tubes
M3 x 30mm bolts and nuts
(Recommended) Sealant such as blue silicone
(Optional) Lubricant such as vaseline (petroleum jelly)
(Optional) Something to make 3D printed parts airtight. Impregnating agent "waterdichtmaken.nl" works fine.
Stanley knife with 9mm blade size
Drill with right size for tightly fitting tubes
Pressurized air source (compressor, ...)
Assembly instruction videos for similar pneumatic devices
Assembly is very similar to the pneumatic gripper and Bourke engine models, for which videos with assembly instructions are available: https://www.thingiverse.com/thing:2738707 and https://www.thingiverse.com/thing:2813533 .
Verify that pistons can slide within middle housing. Grind sides if necessary.
(Optional) Make housing airtight with impregnating agent, e.g. "waterdichtmaken.nl" or some varnish.
Cut six pneumatic tubes, fix them in the holes of the middle housing. Enlarge holes with a drill (3.8 mm etc) if necessary. If tubes are too loose, glue them to the housing.
Cut six seals with the seal cutting tool. First cut square pieces about 30x30 mm with scissors, then position it on the cut block, then put the cap on it, and then make the four cut lines with the knife. For each cut line, first fully insert the knife, then move the knife downwards (press tightly) and back up. It is essential that the dimensions are correct (20.2 x 20.2 mm), deviations ideally under 0.1 mm (watch gripper / Bourke engine assembly video).
Apply blue silicone on top and bottom edges of middle housing. Apply vaseline to pistons and seals. Assemble together as in picture. The seals are oriented such that the larger side (20.2 x 20.2 mm) faces the pneumatic tube, and the smaller side faces the piston.
Insert 28 screws and nuts, tighten all of them.
Test all six tubes with pneumatic air supply at low pressure (~ 1 bar). Sometimes the seal is not in the right position, in this case apply pressure to the other end of the cylinder and repeat, until the seals are properly positioned against the pistons.
For each cylinder, connect its pair of tubes to a 5/2-way valve, and drive the three valves with a microcontroller with the usual servo driving schematics (e.g. TIP120).
Program the software to drive each valve in turn, and enjoy the force of your pneumatic linear stepper motor!