A pendulum of sand draws Lissajous figures. A video made by the markhack YouTube channel. A container filled with plastic sand, suspended by a thread is a pendulum. The person made swing the pendulum making a pretty Lissajous figures through the sand flowing from the container. Lissajous curve is the trajectory of a point which the rectangular components have a sinusoidal movement (copied pasted from Wikipedia). Music: Go Not Gently by Audionautix