Conversion from OBJ to 3DS is not supported yet :(

OBJ

OBJ is a geometry definition file format (.obj extension) first developed by Wavefront Technologies for its Advanced Visualizer animation package.

The OBJ file format is a simple data-format that represents 3D geometry alone — namely, the position of each vertex, the UV position of each texture coordinate vertex, vertex normals, and the faces that make each polygon defined as a list of vertices, and texture vertices.

Vertices are stored in a counter-clockwise order by default, making explicit declaration of face normals unnecessary. OBJ coordinates have no units, but OBJ files can contain scale information in a human readable comment line.

3DS

3DS is one of the file formats used by the Autodesk 3D modeling, animation and rendering software. It once was native for the old Autodesk 3D Studio DOS and eventually has grown to become a de facto industry standard for transferring models between 3D programs, or for storing models for 3D resource catalogs.

3DS is aimed at providing an import/export format, retaining only essential geometry, texture and lighting data.