Throughout history, humans have used periscopes for their utility. Naval ships would peek above water while remaining submerged; troops in WWI used them to see out of their trenches without the risk of being shot. It's been said that in the early 15th century, Johannes Gutenberg, the father of the printing press, invented a periscope to simply see above people's heads during a parade.
Today, periscopes are often used as toys, but that doesn't make them any less interesting. Case in point: The EyeTeleporter, a cardboard periscope that lets you see the world from three different vantage points that's now raising funds on Kickstarter. Juste Kostikovaite and Aurimas Lazinskas created the EyeTeleporter as a way to explore what it might be like if your eyes were in your stomach, or in the back of your head, or three feet above what you usually see.
Like most simple periscopes, The EyeTeleporter is made from cardboard and two mirrored pieces of acrylic that are situated at the top and bottom of the periscope at 45 degree angles. The cardboard fits over your head like a Daft Punk helmet, allowing you to explore hands-free with your new perspective.