When printed with a .1mm layer, these caps provide a range of offsets from .1mm to 5.8mm by simply dropping a cap over the head of the Z-Axis stop bolt. Make sure your bed is good and level before printing these. The different thicknesses are not identified in the model. I'm going to mark them with a Sharpie before I pull them off the built platform.
https://grabcad.com/library/makergear-m2-z-axis-caps-1