Nathan Letwory aka jesterKing is working on Blender add-on to import 3dm file in with some curves and annotation, 3D objects are in mesh, until Blender introduce trimmed capability but I think it don't happen soon, works with Linux, Windows and MacOS, the [b]import_3dm v0.0.12[/b] add-on can be downloaded from GitHub https://github.com/jesterKing/import_3dm/releases or directly at https://www.rhino3d.com/download/rhino/8/import_3dm/
