Oscillating Cylinder Motor for LEGO

You can see it in action here on Youtube.

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

Z_Plate_ALL_PARTS.stl contains all the parts on one plate.
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, 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:

No assembly video, consider it being also a puzzle. And use this demo in 3d viewer as a guide https://skfb.ly/6ZxOs:

1. Cut a finger tip off a glove
2. Put in onto a *4_3_Cylinder_Ring* part
3. Insert the *4_1_Piston* into the *2_1_Cylinder_L_Front*, it should move freely
4. Put the *4_2_Piston_Washer* onto the piston end
5. Put the 2nd washer, so the glove finger tip would be fixed between the washers
6. Insert the Cylinder Ring into the Cylinder, remove the slack from the glove finger
7. Attach the *2_2_Cylinder_L_Back* with 3 M3x6 bolts
8. File down the flat part (with intake holes) of the assembled cylinder to remove the seam and layer lines
9. File down a little bit the flat parts (with air holes) of the *1_1_Base*
10. Insert the *1_3_Axle_Pin* into the *1_1_Base*
11. Use the model in 3d viewer as a guide for the remaining parts
12. 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
13. You may use some lube on the piston shaft and the other rubbing parts

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.