From exocad documentation
When using the model without plate, the next step of the model creator is building the model and separate dies which fit within the model. The wizard is now in the model design and has two tabs, Model and Bottom.
The Model tab parameters are:
5. Anticipate milling - tool diameter compensation
6. Smallest tool diameter slider. Available only when Anticipate milling box is checked
7. You should click Run after changing a parameter, in order to re-calculate the model
8. This will launch the scan data editor.
Here's an illustration of the areas affected by the respective parameters:
Once the calculation has finished, the output .stl files will be saved in the Project Directory.