It looksl ike that the most convenient (and free) way to convert 3D models from OBJ format to 3ds Max graphics (.3ds) would be to use Blender or the FBX Converter from Autodesk. Other than that, you plenty of other 3D modeling / CAD tools support export to 3DS format, either natively or through some dedicated plugin that needs to be installed in other to offer tools to convert obj to 3ds.
Open OBJ file Open 3DS file3D viewer and converter with huge file type support
A CAD 3D geometry translation software
A converter for 3D formats
An online CAD conversion service
A web-based freemium 3D computer graphics software
An FBX convertor utility from Autodesk
A command line converter for 3D format
A free online 3D model conversion service
A commercial online CAD converter
A 3D CAD translation software