Physical Audio has released a beta version of a new physical modeling synth, Derailer. You can hear it in action with a Roli Seaboard in a video on Physical Audio's website. Here's their description of it...

Derailer is 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.

System requirements: macOS 10.9 ~ 10.12, Sandy Bridge or newer processor

Derailer is currently in beta, and is free to use.