The Musical Ruler with Songbook is a metric ruler that is marked with musical notes and can be played by flicking it off the edge of a hard surface. The ruler and accompanying songbook are available for purchase from ThinkGeek.
Each Musical Ruler with Songbook comes with (guess what?) one musical ruler and one songbook. The songbook will show you how to play it and some basic songs and history. We’ll let you in on a secret: you really can play the Musical Ruler! Place your fingers on the finger dots and move it so it overhangs a desk or table. Move it to the mark on the ruler corresponding to the note you want and flick. Like any instrument, it’s easy to make a noise but it takes practice, practice, practice to make music. We know you can do it. Heck, after a couple of minutes with the Musical Ruler with Songbook, we were playing Beethoven! Seriously. We were. In the bathroom here (glorious acoustics).
images via ThinkGeek