Dutch artist Sam Van Doorn creates art with a pinball machine. Or rather, he documents the movements of a pinball doing its thing in a way that illustrates the physics of the game.
A poster is placed on top of the machine, which has a grid printed on it. Based on this grid you can structure your playing field to your desire. By playing the machine the balls create an unpredictable pattern, dependent on the interaction between the user and the machine. The better you are as a player, the better the poster that you create.