Conversion from 3DM to Sketchup is not supported yet :(

A 3DM file is a native file format for 3D models in Rhinoceros CAD application software. It contains surface, point and curve information.

3DM files can be exported in both NURBS (non-uniform rational B-spline) and polygon mesh representations, making it possible for other CAD / CAM / CAE / graphic design software to edit those models.

In addition to Rhino CAD software, 3DM files can be opened with Autodesk Fusion 360.

An SKP file is a three-dimensional model created by SketchUp, a 3D design program. It contains a model with wireframes, shades, edge effects, and textures.

The SKP file enables conceptual designs to be created, viewed, and shared quickly and easily. When you create a new document and save it in SketchUp the SKP file is created to store the document and its contents. SKP files can also be used to store SketchUp components. Components may be made by you or another user and can be imported into an SKP document to be inserted into your model.