You probably cannot directly convert Canvas drawings (.cnv) to Canvas 3D models (.3dc). However, you may be able to use the drawing as a texture for the 3D model itself, so in essence somehow transform the data, but you will need the model as well anyway.
Convert Canvas drawing to Canvas 3D model.
We found one software available in the database for this conversion.
Microsoft Windows software - convert cnv to 3dc on Windows
A drawing software used to create technical illustrations and graphics
Convert from cnv 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.