You can see it in action here on Youtube.

Work animation in 3d viewer (Sketchfab): https://skfb.ly/6ZxOs

Can be printed with 0.6 (or smaller) nozzle, at 0.2 layer height.
Takes about 7 hours (and 14m of filament) to print at 20mm/s.

Way more leaky than the [Radial Motor](https://www.thingiverse.com/thing:4197583) , but looks a bit cooler, with all the moving parts exposed. Runs for about 15 seconds on a double wall balloon (one balloon inserted into another). Can run on a single balloon as well, just needs a lip from the 2nd balloon for the sealing.

Extra parts needed:

• Nitrile or PET glove fingers for the membranes
• Bolts: M3x6 x9, M3x8(or 10) x2, m3x14 x2, m3x10(or longer) x2, m3x26 x1
• M3 nuts x4
• Two air balloons

Assembly:

Will add an assembly video a bit later, for now you can use this demo in 3d viewer as a guide https://skfb.ly/6ZxOs:

• Cut a finger tip off a glove
• Put in onto a 4_3_Cylinder_Ring part
• Insert the 4_1_Piston into the 2_1_Cylinder_L_Front, it should move freely
• Put the 4_2_Piston_Washer onto the piston end
• Put the 2nd washer, so the glove finger tip would be fixed between the washers
• Insert the Cylinder Ring into the Cylinder, remove the slack from the glove finger
• Attach the 2_2_Cylinder_L_Back with 3 M3x6 bolts
• File down the flat part (with intake holes) of the assembled cylinder to remove the seam and layer lines
• File down a little bit the flat parts (with air holes) of the 1_1_Base
• Insert the 1_3_Axle_Pin into the 1_1_Base
• Use the model in 3d viewer as a guide for the remaining parts
• After the assembly, press the cylinders towards the base with the bolts at the sides - there shouldn't be too much friction between the cylinder and the base
• You may use some lube on the piston and the other rubbing parts

"Z_Plate_ALL_PARTS.stl", as the name suggests, contains all the parts on one plate.

Parts with X_ in their names are optional - you may assemble one-cylinder motor using the X_3_1_OneCylinder_Lid part, or a motor with single-acting cylinders using ..._HalfCylinder parts. The second one works quite poorly even on 2-walled balloon, but runs for almost 30 seconds and makes a cooler sound.