This weekend I hacked a version of the Oculus Rift stereoscopic 3D headmounted displays using household items.
The main technique was from Andrew Noske.
But not following the instructions, I made it out of lightweight card stock and used an $8 3 pack of 3+ reading glasses, and a bit of velcro on a nylon strap (which holds the weight of the iPhone or Android from the brim of your favorite baseball cap).
The pictures only show 2 pair of glasses, but I added the third to fine tune the focus. Unlike Google Cardboard, this has a full screen field-of-view (Google’s is only a small circle in the center of the square left/right halves).
BTW – Some of the free Hasbro My3D games work great (sensing head motion and use the holes in the bottom for iPhone to control the buttons).
If you’re wanting hands free utility, the baseball cap as a head strap works better to accommodate the weight of the phone (which is a bit further out from Cardboard’s shorter/smaller focal length). Without this, it is a bit heavy on the bridge of the nose and pulls away from the eye-glass ear grips.