This interactive harmonograph simulation was inspired by a Three-Pendulum Rotary Harmonograph, except that here all three pendulums are rotary. Each pendulum can be made to swing in only one direction by setting one of its amplitudes to zero.
The 'scene' shows a top view of the harmonograph. Use this to visualise how the pendulums are affected when playing around with the 'settings'.
See also: The simulation of another type of harmonograph.