This video brought a smile to our faces. [Griffin Milsap] is creating live music using an orchestra of solenoid instruments. Each solenoid is set up to strike an object such as a bowl or mug. The trigger mechanism is a light sensor inside of a ping-pong ball. The collection of instruments is conducted by a motor-mounted green laser. When the beam of light passes by one of the ping-pong balls the photo transistor inside actuates the solenoid and a note is played. The pitches are quite a bit more random than the Robo-vibe, but it’s delightful to hear the results that [Griffin] has achieved.