A miniature 3D printable inline four-cylinder flat-plane engine. Can be customized or edited on demand. More file formats could be provided if needed.
STL (Stereolithography, filesize: 8 MB), SLDPRT (SolidWorks, filesize: 4 MB), IGE (IGES, filesize: 8 MB), STP (STEP, filesize: 4 MB)