Harmonograph
Decaying pendulum swings near simple frequency ratios, drawn as one continuous line.
Pens
Color follows the pendulums as their motion decays. Starts with 3 pens and works with anywhere from 1 to 8.
Settings
X frequency, Y frequency, Detune, X phase°, Y phase°, Amplitude, Rotary pendulum, Strength, Frequency, Phase°, Duration (cycles), Damping, Damping skew, Smoothness.
The preview uses the default settings on A4. Press R in the app for random variations. The SVG export is in millimetres with one Inkscape layer per pen, so it works with the AxiDraw extension, vpype and saxi.