A rig is a character manipulation tool used to move a character to create animation. Rigs can only be applied to characters which have been characterized.

You can use Python to characterize, create control-rigs, set new control-rigs as character inputs, load/merge characters into scenes, and map character skeletons to new templates.

The class FBConstraintRelation contains functions for creating receiver, function, and sender boxes, and for setting and getting their positions.

You can customize MotionBuilder’s 3ds Max biped template. At startup, every Python file in the config\CharacterTemplate is added to the Character Folder in Asset Browser.

You can create your own biped template for different tools, however, note that:

• The script must not create a new character.
• You must characterize the last added character on the scene: FBSystem().Scene.Characters[len(FBSystem().Scene.Characters) - 1].
• The 3dsMaxBipedTemplate.py script can be modified to accommodate a custom skeleton.

See also the sample script CreateAndPopulateAConstraintRelation.py.