Hi Rich - MoI is focused on editing NURBS surfaces and not polygon data.

So the fundamental problem is that you're trying to import polygon data into MoI and not NURBS data.

Rhino 3DM files can contain a variety of different kinds of things in them, like NURBS surfaces and solids, polygon mesh data, dimension annotations, spotlights, etc... of all those kinds of things MoI only reads the NURBS data.

When you did the export from Cinema4D to 3DM, it created a 3DM file that contained only polygon mesh objects in it and not any NURBS objects in it, so that's why nothing came into MoI.

If you want to directly edit a polygon mesh object, you'll need to do that in a polygon mesh modeler instead of MoI.

If you just want to use the polygon mesh object as a kind of visual guide, then that is possible by exporting from Cinema4D to OBJ format, and then using the OBJ to Wireframe 3DM converter available here: http://moi3d.com/wiki/Resources#Obj23dmWireframe_converter - that will convert the wire outline of all the polygons in the OBJ file into line segments in a 3DM file, and then MoI will be able to open that 3DM file and you'll see a wireframe of your mesh object in MoI.

- Michael