MIT Physics Demo - Spray Paint Oscillator
[color=rgb(51,51,51)][font=arial][size=3]A can of spray paint is attached to a spring oscillator. A roll of paper is run past the oscillating can. The result is a sine wave -[/size][/font][/color][url="http://en.wikipedia.org/wiki/Sine_wave"]http://en.wikipedia.org/wiki/Sine_wave[/url][color=rgb(51,51,51)][font=arial][size=3] - on the paper.[/size][/font][/color]