This looks like a cool project that uses an Arduino & Processing to generate LED graphics based on MIDI inputs. I really like how it is housed inside an old slide viewer.

A while ago I found an interesting post on the arduino forums about a guy who made a 8×8 LED panel for his friend to use to visualise when playing music. So when I was browsing my local thrift-store I found an old slide viewer (for you kids, it’s an old pre digital way to take photo’s).

More about Opal: Arduino based LED and MIDI [arduino.cc]

In the Maker Shed:
Makershedsmall
Arduino Family
Make: Arduino