A harmonograph draws with a pen suspended from two or more pendulums that swing at slightly different frequencies. Because the pendulums are almost but not quite in sync, their combined x/y/z motion traces looping Lissajous-like curves instead of a simple circle. The exact ratio between the pendulum frequencies, and their relative phase offsets, determines whether the pattern looks like a rose, a spiral, or a tangled knot. Nudging the frequency below changes that ratio live and reshapes the curve as it is drawn.