I just saw this posted at 3dPrintingindustry. It's a toy that is offered at Shapeways for $12. It's called Wave. Basically the device is a syphon which has to stay in balance. Once water flows into one end it becomes unbalanced and begins syphoning water from one end to the other. Check out the video to understand what I mean:




Wave can be purchased on Shapeways here: http://www.shapeways.com/model/1291002/wave.html