About this 3D model

**UPDATE: Nuts/Bolts/Holes enlarged to make printing easier. You can also skip the printed nuts & bolts opting to use real M3 bolts if you want.** Working piston and rod with wristpin, threaded rod bolts, washers, and nuts. The real wristpin retainer was going to be tricky, so I just made two tapered pins to wedge in at angles inside the piston instead. 100% parametric, but complicated. Scaling should be no problem, but you may need to tweak the settings to compensate if you make things too out of proportion.