Mixamo's Auto-Rigger can take any bipedal 3D character mesh and automatically rig it in under 2 minutes. Below are some example workflows for extracting your 3D mesh from Modo, ZBrush, and Blender and running them through the Mixamo Auto-Rigger.
Upload your 3D character for automatic rigging by going here: http://www.mixamo.com/upload_character
Did you know you can automatically create a 3ds Max Biped out of your Mixamo Auto-Rig?

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