Chladni
Nodal lines of vibrating square and circular plates, with sand bands hugging them.
Pens
Nodal lines anchor the drawing. Colors distinguish vibration bands on either side. Starts with 4 pens and works with anywhere from 1 to 8.
Settings
Plate, n, m, Mix, Bands, Band spacing (mm), Band spread, Grid resolution (mm).
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.