Physical Audio released the first public beta of PA3 Derailer, a physical modelling system with two basic elements. One is a metal bar that you can strike or bow. The other is a nonlinear mass/spring connection. This allows you to join two bars together so that vibrations from one create sympathetic resonance in the other. By connecting multiple bars you can create new instruments that have their own unique sound.
There are 37 strike bars, 5 resonators, and up to 81 connections to play with. The adjustable physical parameters and nonlinearity of the connections produce a wide range of tonal variation that reacts to striking velocity or bowing pressure.
More info here: Physical Audio