David has never created a kinetic scupture that keeps time. He likes to maximize the motion and that design goal is at odds with a time keeping device. But we still do love those wooden clocks. Here is a very intircate one that I found on the web recently. Check out the insides.
The Russian Wooden Gadgets site notes the following, "Such Russian clocks were produced by the Bronnikov family from Russia. For three generations they mastered their skills on crafting light-weight fully functional wooden pocket clocks. Such gadgets were true hit back then, among their customers there were Russian Tzars and other high society members. They were sending their samples to the international exhibitions of Paris and New York to make foreign people awe. The price of such wooden clocks exceeded of those of gold. Not many of those survived Russian revolution and communist reign. Those who did are a rare guest of antique shops priced at around $20,000 for each."