MAX has this ‘spring’ controller that makes it easy to simulate objects suspended on spring (except the spring is invisible). The spring action can be influenced by one or more objects, dampening, force etc. Applying spring controllers to helpers and linking stretchy bones to those helpers, is a cool recipe for bouncing bellies and boobs.
Now I don’t see the word “Spring” in under Constraints OR Modifiers in Blender 2.54. :hmm: I’m wondering how one can simulate a realistic (or near real) bounce on a character’s boobs without actually animating/keying the bounces.