Cut your cardboard into some precise shapes, and you can fold it into a headset that looks like a bit like boxy, thirft-store Oculus Rift. Slide your Android phone into the slot on the other side of the optical lenses and, blammo, you've got a VR headset.
Wish Granted: Here's Your Portable Holodeck
Next you'll need to download the Cardboard app to check out the handful of VR demo applications. If you really want to get serious, you can also download the experimental VR Toolkit, which Google is providing to developers in hopes of spurring a whole new category of VR-by-phone apps.
"By making it easy and inexpensive to experiment with VR, we hope to encourage developers to build the next generation of immersive digital experiences and make them available to everyone." says the team on the project page. "We want everyone to experience virtual reality in a simple, fun, and inexpensive way."
Good thing, because those old Pink Floyd records are expensive.