Piston and Rod with bolts, nuts, and pins included

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.