Cardboard (Google)

Cardboard is one of those things that many people wondered if it was one more of Google's famous "April Fool" jokes (though it came out in the summer), but it is actually a real concept. It's literally a piece of cardboard cut and folded in accordance with a pattern or purchased pre-made, which you place an Android device into in order to put it up to your eyes in the proper configuration to enjoy virtual reality presented using the "Cardboard SDK" (software development kit).

Links

 * Official site
 * Developer overview
 * Google Cardboard: Seriously Fun
 * Google Cardboard Gets Software Development Kit For VR Apps