Models saved in the 3D NURBS CAD format (.3dm) can be probably exported and converted to other 3D model data files, including ISO STEP product data files (.stp, .step). Good option for this are dedicated 3D model / CAD translation software or even some modeling programs with broad file support.
Convert 3D NURBS CAD file to ISO-10303 STEP product data.
We have found 3 software records in our database eligible for .3dm to .stp file format conversion.
Microsoft Windows software - convert 3dm to stp on Windows
3D viewer and converter with huge file type support
Convert from 3dm file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned 3dm to stp. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A converter for 3D formats
A CAD converter with huge format support