This calibration model is a bit different than those other models.

1. it's larger in x and y, allowing for more accurate measurements of the resulting model, and therefore improving calibration
2. its taller in z, again, allowing for more accuracy with using the same precision instrument.
3. There are internal and external dimensions to measure, allowing for a cross check
4. you can measure the top and bottom of the model allowing for a measurement on the impact of elephant foot
5. there are diagonals, with measurements included that give you a check for racking on x and y, which many calibration models are terrible at measuring.

I'm craving feedback on how to improve, so please drop me a pm or review the model with thoughts on how it helped you or could be improved.