This is a series of 15 pendulums using golf balls. The shortest pendulum swings 57 times per minute. The next shortest one swings 56 times per minute, and so on, down to 43 swings per minute. This creates some pretty cool effects, the two most ostensible being that at 30 seconds (consecutive pendulums are at opposing positions in their swings) and at 60 seconds (all 15 pendulums are in sync as they were when they started). All told, this took about 20 hours to construct and tune. The tuning had to be accurate down to the millimeter to obtain the precision observed!