This video takes a look at making a Robotic Xylophone with homemade solenoids and a Nerdkit robotic brain.

The Nerdkit microcontroller is available for $79.99.

via nerdkits:

In this video tutorial we document how we built our robotic xylophone. We take this opportunity to not only describe how we built the xylophone from scratch, but we we also cover solenoids, a little bit of the theory of electromagnets, and even shift registers! As always, we explain the concepts behind the project as well as provide the source code so you can work these ideas into your own projects.

For a complete description of this project, please visit our video tutorial page at: http://www.nerdkits.com/videos/robotic_xylophone/