This is a assembly of piston, conection rod, screws, pin and nuts, all was modeled in SolidWorks and imported to .PLY, .XT and .STL, all is functional and printable, the thread of the screw and nut is in a real dimensions based in engineering rules.
The dimensions of the assembly:diamiter: 8cmheight: 21cm
Buying this model you'll recieve:The assembly and all parts to print.