If you're tired of crowding around a laptop or smartphone to watch a movie or video clip, this DIY projector will throw it up on the wall for all to see. Plus, it shouldn't cost you too much in parts at your local hardware store.
YouTuber and Instructables user The King of Random put this tutorial together to build a projector screen from really affordable components. All you'll need is a large cardboard box, some duct tape and a Fresnel lens. He picked up the Fresnel lens from eBay, a free cardboard box and a roll of duct tape. If you want a projector screen, he also shows you how to make one from a styrene sheet.
Since the projector only gets light from your device's screen, it will be pretty dim. For the best possible image quality and sharpness, use a bright screen (a laptop would work better than a smartphone) and make sure to keep the lights off, curtains closed, and put the projector as close to the screen as possible.
Finally, the lens will flip the image horizontally and vertically, so after you mount your device, text will appear backwards. Not an issue for action movies, but news or subtitles could be a problem. If you can do this on the cheap the way The King of Random did, it's a fun and portable project, not to mention a fun introduction to optics for anyone interested in a little physics.
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