3DM (Rhino 3D Model)
The 3DM CAD file format
3DM files are used for 3D image files created with the McNeel Rhino 3D image editing and creation program. It is an open source format and the native file of Rhinoceros. McNeel Rhino is available for Windows computers and for Mac, but there's also an OSX version for Mac computers.
Technical details of 3DM files
The 3DM format allows to save and exchange 3D geometry across different graphic software as well as CAD, CAM and CAE. To do so, the file uses NURBS representations together with polygon mesh representations. Thus, software developers and designers can easily and accurately transfer images containing 3D geometry between applications and devices.