It seems you can import *.stl (3D printing) files to programs like AccuTrans 3D and export them as *.lwob LigthWave 3D object files.
Convert Stereolithography CAD file to LightWave 3D object file.
We found one software available in the database for this conversion.
Microsoft Windows software - convert stl to lwob on Windows
A CAD 3D geometry translation software
Convert from stl file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.