A combination of touch-screen and sound synthesis technology produces the reactable.
Visit the reactable web-site at https://www.iua.upf.es/mtg/reactable/
The reactable is a multi-user electro-acoustic music instrument with a tabletop tangible user interface. Several simultaneous performers share complete control over the instrument by moving physical artefacts on the table surface and constructing different audio topologies in a kind of tangible modular synthesizer or graspable flow-controlled programming language.
Also has a wikipedia entry at https://en.wikipedia.org/wiki/ReacTable