When doing a SaveAs of a non-mm model (e.g. inches), the SaveAs dialog box should have an option to scale the model to mm when saving as STL.
This would make it very easy to design a model in Rhino in inches, for example, export it as STL (but scaled) and then import into a slicer, like Cura, without loosing dimensional information.
Hi Mike -
When you import an STL file into Rhino, you can set the “STL Model Units”. From what you are saying, your slicer doesn’t have that option. Perhaps you could ask them to add that option.
In Rhino, you could create a macro that changes the document units, exports, and changes the units back.
-DocumentProperties Units UnitSystem=Millimeter Yes EnterEnd All -Export Browse EnterEnd Undo