Since the kaleidoscope was invented in 1816, numerous artisans around the world have expanded on its design, making it a true art form, with each one as different as the artist who created it. Over the years, different types of kaleidoscopes have emerged, including the wheel kaleidoscope. These have one or more disc-shaped chambers at the end of the scope containing small objects such as flowers, beads, or glass. As the discs are turned, the objects inside move, changing the image. Another type of kaleidoscope is the chamber, which has a fixed case inside. The case holds various colored items that free-fall as the scope is turned. Liquid chamber kaleidoscopes are similar, except that the objects float in a liquid, usually glycerin. Yet another type is the teleidoscope. This device has a lens instead of an object case at the end. With a teleidoscope, rather than seeing objects within the device, viewers look at objects around them that are distorted through infinitely changing designs. There are also two-sided kaleidoscopes that allow two people to view the images together from opposite sides. Another modern type is the lamascope, an interactive kaleidoscope that lets users create designs with their bodies. These designs are then projected onto a screen, making viewers themselves part of the art. Art director Antonio Alcalá designed the Kaleidoscope Flower stamps using the art of graphic artists Petra and Nicole Kapitza. Each stamp pictures the same flower shape with different colors, creating the illusion that the patterns recede or move forward.