Good way of showing a student the mechanics of how a engine converts back and forth motion to rotation. Was fun designing in my new AlibreCad program. All movments could be simulated and checked for clearance before printing. It came out exactly as the simulator showed. After assembling and a little sanding of the cylinder it turned very smoothly.

You can use bolts or screws to assembe but I just glue on the head and bearing, crank and other part move as normal.

Sorry for the confusion on having a seprate file for the parts. I have it in the correct fold now and it should easy to download all the parts now.

Also I have added all the Alibre CAD files in a ZIP with all the motion constrains inplace for you Alibre CAD fans. Have fun and I'm look forward to your mods/derivatives of it.