Kinetic sculptures in wood...

Kinetic sculptures in wood...  Completely by accident, this morning I ran across the work of David C. Roy.  The video at right shows one example; more here and here.  I find these sculptures both beautiful and fascinating. 

Mr. Roy limits his sculptures to purely mechanical motion (springs, weights, etc.) and eschews anything like an electric motor.  Personally, I don't think they'd suffer if motorized.  Beautiful things!  And it makes me wonder if I could do something like them...