Create Digital Music has a great post on [Luca De Rosso]’s OTTO. Built as part of his masters’ thesis, it’s a unique tangible music interface. You load a sample into the software which displays it on the instrument surface. The user can then manipulate the sample using various hardware inputs while watching the LED representation. The device uses just one Arduino for the display and inputs. It works with Max/MSP and is designed to give the performer only the information they truly need. You can find more pictures of the device on Flickr and a picture of the guts on CDM. Embedded below is the ‘Getting Started’ video that shows it in use.