The BladeAxe and the PlateAxe are two physical-model-based instruments. They use an "hybrid" approach to physical modelling where part of the sound of the instrument is created in the real world, and part of it is virtual and computed.
While the BladeAxe looks like a guitar, it can be used to play any kind of plucked string and percussion instrument. The sound created by the fingers (or any object) of the performer on the pieces of plastic placed on the front face of the interface are picked up, processed and used to drive the virtual strings/objects, etc. This literally "couples" the performer with the virtual instrument providing a level of control and interaction similar to the one of a "real-world" object.
The sound of the BladeAxe is computed on an iPad that is also used to change the pitch of the various physical models as well as their parameters.
One of the previous version of the BladeAxe