The Computational Design Lab at Carnegie Mellon University has an interesting archive of current and previous projects. One that particularly caught my eye was Bach Blocks. A physical tangible instrument to encourage children to create orginal music. Rhythms and harmonys are created by placing the blocks in different patterns. The colour of the blocks is used to identify the pitch and the size of the block determines the beat length.

Reactable is a tabletop tangible user interface allowing several performers to control the instrument simultaneously. By moving physical objects on the table surface, users can interact with one another (locally or remotely). Researched and developed by the “Interactive Sonic Systems” team at Universitat Pompeu Fabra in Barcelona Spain.

A video camera beneath the translucent table tracks the position and relationship between the objects and instant visual feedback is displayed by a projector.