Mini delta was calibrated by printing Calibration.stl model and then measuring the actual X, Y, Z dimensions. We can scale the model accordingly. This gives accurate enough models in practice. Note that these numbers are specific to my printer.
Most of these models are also available on thingiverse
Expected X = Y = Z = 20
Actuals:
X = 19.59
= 102.10%
Y = 19.7 19.54 19.50
= 19.41
= 103.04%
Z = 19.66
= 101.73%