Harmonograph — Spectrum

Play a chord — MIDI, computer keys, or the on-screen piano — and watch the harmony draw itself as a Victorian pendulum figure where every note draws its own colored thread: hues step by the circle of fifths, so a triad weaves from three kindred colors. Sculpt it live — the sustain pedal (Space / CC64) accretes layered chords, the mod-wheel (CC1 / ↑↓) sweeps pendulum damping from loose sprawl to tight spiral, harder strikes draw brighter ink. Export the figure as a PNG or a printable vector SVG specimen.