Some features include: Magnets (simple simulation, but still useful), springs (and yes, the spring between them is shown and stretched the right amount), Newtonian Gravity(not shown in screenie). Last but most: Material simulation. Material simulation autopythonicly creates constraints and breaks the constraint if too high a force is applyed. And the user has a variety of settings to set for the material. Note: All my example material sims are single layer thick (like cloth), but it works for multilayer thick also.
This isn’t a finished project but will go on, I have vague plans to do some documentation, the most boring part.
Very last and very most: Get the .blend at http://uploader.polorix.net//files/551/physdemo2.blend
There are several scenes to checkout. It’s recommended to “enable all frames”