drawing board

 
A horizontal platform is suspended by four ropes. Upon the platform is a sheet of paper against which a marking pen is held by a stationary support. The platform is started swinging in the manner of a pendulum and an interesting pattern is drawn on the paper.
 
The pen can be lifted from the paper, the platform stopped, a pen of a different color put in the holder and the platform started again to cause a second different pattern to be added to the drawing. Quite impressive patterns sometimes are made. Four large eyescrews can hang four ropes from the ceiling of a garage or basement. The platform can be about 2 by 2 feet. Try to get equal tension on all of the ropes. The pen holder can be made from two yardsticks. See diagram on next screen. Drill pivot holes about 8 inches from one end. Use nails through the pivot holes driven into a piece of 4 by 4 post to hold the yardsticks. The nails should be a loose fit and the 4 by 4 should be securely anchored to a solid base. If the platform is only a few inches above the floor, it will be easier to make a stable pen holder.
 
A block of wood is fastened between the yardsticks as shown. Place weights on the block to balance the weight of the yardsticks so that very little pressure is on the pen's tip.
 
Place 2 or more bricks on the platform and use trial and error for placing them to give the best patterns. You should be able to get a repeating pattern with each repetition slightly smaller than the one before. You may find it helpful to have one person hold the pen holder while another person starts or stops the platform.