You still have to use D3Edit to convert your level, make rooms, place objects, etc even if you use a model editor. And I don't think 3DS max is necessary, pretty sure something like blender would work, but I'll wait for confirmation from the more model-savvy folks here.
You can use blender to convert to a format readable by D3 edit, but not much more than that.Usually goes from .blend > .dxf > .orfor if you want a model.blend > .dxf > .orf > .oofWouldn't recommend it though because it usually messes up all the normals on the models, but you can go ahead with that if you know D3 Edit real well, Which I don't.EDIT: And yes, you could also convert your .blend files to .3ds and then to .orf or .oof, whichever is your choice. But I don't use 3DS Max, so I've never really had a reason to convert a .blend to .3ds. I could definately try that sometime too.. it might work better than .dxf . I actually don't know of any converters that go from .3ds to .orf, so that'd also be helpful to know too. :3
The part about .blends doesn't exactly apply to 3DS Max, considering that 3DS Max doesn't ever output .blends because .blend files are quite Blender specific Wish I could provide more insight, but there were definitely tools to convert 3DS files into rooms you can then assemble via d3Edit.
Reading 'adding in little new things' let me smile.
IMO there no is need using other stuff than Descent3 Editor for building good and eyecandy Descent3 levels and missions.