I am on a Mac. I am currently looking for a tool that is able to correctly convert .obj files (Wavefront) to .3ds files (Autodesk 3ds Max).
I tried Blender but the exported file failed to include the smoothing groups.
What do you recommend I use?
Here's a link to the autodesk docs about importing .obj files in 3ds Max. The .3ds file format isn't something open and it's really tied to the internal workings of 3ds Max, so you can't really count on an external exporter or something like that.
Source: I worked on 3ds Max.