This labeled kinematic engine model helps visualize piston movement during a 2-stroke engine cycle.  Turning the knob at where the conrod attaches to the crankshaft moves the piston from BDC to TDC.  Parts of the 2-stroke engine are labeled, but if there are any other labels you think I should add let me know!

For dimensional tolerances, I suggest printing with a 0.1-0.2 mm layer height, and infill between 10-20%.