This is a stand-alone Public Domain model of a Wankel Engine in OpenSCAD. This is intended more as an example of an interesting mechanism than as a useful engine.See http://en.wikipedia.org/wiki/Wankel_engineThe file uses code appropriated from Leemon Baird's PublicDomainGearV1.1.scad which can be found here: http://www.thingiverse.com/thing:5505Download and view with OpenSCAD, or try and print the STLs!