Using Adobe Photoshop (possibly with plug-ins) it might be possible to import Universal 3D files and export them to a Photo CD graphics PCG format.
Convert Universal 3D format graphics to Photo CD graphic file.
We found one software available in the database for this conversion.
Apple macOS / Mac OS X software - convert u3d to pcg on OS X
Mac version of popular digital image editor
Convert from u3d 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.