This engine design is based on a flat two cylinder engine.
The files available for download are slightly different than the model in the pictures. Differences include: reduced number of off the shelf parts, a base for the model, and some minor modifications to some of the parts. The renderings in the picture section show the updated model.
The model in the photographs was printed on an objet. If the design is printed on an FDM machine it may need to be scaled up.
Assembly instructions are included with the parts.
If you print and build this any feedback is much appreciated!