I saw this amazing machine at an auction yesterday. It had a drawing table attached to the top of a pendulum and a pen attached to the top of an other pendulum. when they were set swinging, the pen would draw indicate patterns similar to the old spirograph toy.
The pendulums could be raise and lowered to alter the period of swing and both pendular were independent and could be swung in any direction or in circular motions. Great fun and I thought you would like to see it.
Here are a couple of other pendulum drawing videos if you are excited by this.