https://www.youtube.com/watch?v=zEmN3HBRNC0 https://www.youtube.com/watch?v=XWxHsXHhBeU https://www.youtube.com/watch?v=uWxExhBJ4_c&t=30s https://www.youtube.com/watch?v=TVCq5LRrM78 A few months ago (June, 2017) I posted a video on my YouTube channel (youtube.com/user/popzct0214/videos) of Single Cylinder Air Engine, Experimental. After experiencing more than a few propeller strikes on my fingers, I put in on the shelf and decided not to publish it. Since then, I've had a few requests for the STL files, so here they are. Remember, this engine is experimental and when spinning the 10" propeller is potentially hazardous, so be prepared for precision filing, assembly, and fine adjustments if you decide to print it, and wear full protective gear (gloves, face shield, etc.) if you decide to run it. This design utilizes a cam, pushrod, ball bearing and spring to pressurize the cylinder at the correct time. The design depends on cylinder blow by for exhaust, and as such it is not as efficient, but again it does make an interesting conversation piece and impressive noise. As usual, I probably forgot a file or two or who knows what else, so if you have any questions, please do not hesitate to ask as I do make mistakes in plenty.