SummaryMost of the information that I used to design this came from this PDF: http://www.personal.utulsa.edu/~kenneth-weston/chapter7.pdf I didn't get around to adding the intake/exhaust ports and spark plug. There is a video of this thing here: http://www.flickr.com/photos/53725866@N07/6329093033/InstructionsPrint one of each part (either print all the parts individually or print the crank & eccentric together) Put the rotor and crank in the housing. Put the eccentric on the end of the crank. Spin the crank.