A projector is a popular choice for home theater enthusiasts who like to pretend they're at the cinema. But projectors can be loud, hot, finicky, and expensive. Unless you're ok with a model made from cardboard that you never even have to plug in. It must involve magic, right? Think again.

Barely larger than a couple of old tissue boxes—and possibly even made from them—this smartphone projector will set you back just $20, leaving you lots of money to spend on comfy seating and pre-stickied floors for your media room.

So how does it work without power or cables? It's simple. You just open an access door on the back, slide your smartphone inside while it's playing a movie, and close it back up. The light from your phone's glowing display is magnified ten times through the lens on the front of the projector, making it considerably larger on a nearby wall or screen.

There are a few compromises, of course. Mostly that the projection is dim, small, and blurry, there's no way to use your surround sound system, it prevents you from accessing your phone while a movie is playing, pausing is kind of a pain, there are no volume controls, you can't get it wet, and your friends will laugh at you. But again, it's $20, and recyclable. Your move, Sony. [Prezzybox via Ubergizmo]