I found some cheap glowing juggling balls (4 € per ball) in a DIY store; they were meant as ambient light decoration, but you can actually juggle them, even though they're a litte bit light. I later replaced the three coin-cell batteries with a compartment for 2 AA-type batteries; that made the weight just right, but the added mass also made the entire contraption still more sensitive to falling down.
The photos and videos were made with my Canon PowerShot A520 digital camera. Depending on the shutter speed, longer or shorter movements of the balls are captured. A nice effect results from the permanent color cycling of the balls.
The animation was filmed as a 320x200 video and then converted to an animated GIF file. Unfortunately, the quality and length had to be greatly reduced in order to publish this on the web. The pattern is called Robot or The Machine.
Ingo Karkat, 04-Jan-2006