To set up the viewer, click on the arrow. Then click the arrow or "OK" again to allow the app to access your device to take pictures and record video. Scan the "Google Cardboard Viewer Profile" code ...

In the most high-profile collaboration, Mattel recently announced that it will use Google Cardboard tech and specs to revive its View-Master brand this coming fall.

Google reports that over 500,000 units of its Cardboard viewer has shipped, all from non-Google retail channels.

But first, you have to put your cardboard viewer together. Google provided directions to put together the viewer, which is made from cardboard, velcro, magnets, and lenses (NFC tag optional).

As we walked out of today's Google I/O keynote, we -- and all other keynote attendees -- were handed the second-generation version of Cardboard, Google's low-tech effort at a VR headset. As was ...

The Google Cardboard app lets you use your phone into a VR device, and it's available for free and is designed to work with cheap VR viewers.