Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4019964.

Building off of my earlier sliding valve air engine( https://www.thingiverse.com/thing:2492963), here is a 2 cylinder version. This design runs well, but it needs lots of air.

Included in the files is a list of parts and hardware - See BOM_list.pdf. There are also pictures to help set the eccentric orientation during assembly.

Also a .step file is included if you want to make changes.

Slider_3 was optimized for the single cylinder engine and may be a better option for this engine too. It works well with Slider_2

Here are a couple videos of the engine in action.

https://youtu.be/QOqWBn9rho0

https://youtu.be/rPLHXZ8i-B4