One aspect of traditional 3D animation using clay or plasticine is the ease with which the object can be deformed.
Animators take for granted the ability to interactively press complex objects together.
In 3D computer animation, this ability is severly restricted and any improvement would drastically increase the range and style of animations that can be created within a production environment. This paper presents a simple, fast, geometric approach to controlling the nature, extent and timing of the surface deformations arising from the interpenetration of kinematically controlled animated objects. A kinematic model for collision response. In Fifth Eurographics Workshop on Animation and Simulation, Oslo, Norway, September 1994. Doc 135 Elastically deformable models - Terzopoulos, Platt et al.