It should be possible to convert 3D models saved as .a3d files (Amapi 3D) to other 3D modeling formats, including 3ds Max graphics (.3ds). You will probably have to rely on some dedicated 3D conversion utilities like 3D Object Converter, or similar to sucessfuly convert your 3d model from A3D to 3DS format.
Convert Amapi 3D modeling file to 3ds Max (3D Studio MAX) graphics.
We found one software available in the database for this conversion.
Microsoft Windows software - convert a3d to 3ds on Windows
3D viewer and converter with huge file type support
Convert from a3d 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.