Hi,

I just saw this discussion at the Blender Artists forum, about a free add-on that can import Rhinoceros 3DM files.

https://blenderartists.org/t/import-rhinoceros-3d-files-into-blender/1136070

I'm not sure if it's also fully compatible with MoI 3DM files, but it's definitely interesting.

Regards,

Metin