A kaleidoscope is a cylinder with mirrors containing loose, colored objects such as beads or pebbles and bits of glass. As the viewer looks into one end, light entering the other end creates a colorful pattern. A kaleidoscope operates on the principle of multiple reflection, where several mirrors are placed at an angle to one another, (usually 60°). Typically there are three rectangular mirrors set at 60° to each other so that they form an equilateral triangle. The 60° angle generates an infinite regular grid of duplicate images of the original, with each image having six possible angles and being a mirror image or not. As the tube is rotated, the tumbling of the colored objects presents varying colors and patterns. Arbitrary patterns show up as a beautiful symmetrical pattern created by the reflections. A two-mirror kaleidoscope yields a pattern or patterns isolated against a solid black background, while the three-mirror (closed triangle) type yields a pattern that fills the entire field.