And, in case anyone wants to tinker with the idea, here's an unsuccessful effort to use the spring system approach to do soft-body "bounce" for, well, breasts.  Cough.  Doesn't really work, sadly.  Perhaps it shows how to go about animating the spring simulation across multiple frames, rather than in just one frame....

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Cage can be an opinionated jerk who posts without thinking.  He apologizes for this.  He's honestly not trying to be a turkeyhead.

Cage had some freebies, compatible with Poser 11 and below.  His Python scripts were saved at archive.org, along with the rest of the Morphography site, where they were hosted.