Hi,
I don’t understand the way viscosity is implemented in Panda3D. The manual states that you have to create a physical object and then apply the viscosity to it. But then, what can I do with this physical object ? Apply it to a model ? In this case, how can I apply a force so that the model is deformed ? It is written that actors ar a subclass of physical objects. Are models a subclass of it, too ? Viscosity applies to liquids, so what shall I do if I want a a drop of honey hanging from a bee nest ? Are you sure that what is called viscosity is not in fact elasticity ?
Sorry if my lack of panda knowledge makes me write a lot of rubbish 
You can look in the source code or in the API reference to see what other documentation there might already be for this interface.