I'm not sure of your application or tools available to you....but here are two ways that I know of that works best.
If you are making molds:
If you are exporting objects that are complex with under cuts your going to want to use a 3d printer. There is a volume of information on Zbrush. Check these links http://www.zbrushcentral.com/zbc/search.php?searchid=1422335
If you are using a 3 axis milling machine:
Artcam is very expensive...but... worth every penny if your serious about selling a product. I create a base model in 3d Max export it and add the fine details in Artcam and finally export toolpaths.
You can also import 3ds and STL into Rhino Mastercam and a number of other programs(cant remember when they made the change but I believe Maya 7 in plug'ins can activate "export 3ds")...but the files can be huge and CPU intensive...I've found Artcam to be the best at making the bridge, next best would be Rhino.
Rhino handles these files great if you don't try to modify anything and just produce the toolpaths.