No, really, Google Cardboard is a thing. It is a cardboard case for your smartphone that works in conjunction with compatible apps such as Seene to project 3D images or videos. For those of you that remember the View-Master stereoscope gadget from the 1980s, it works on the same principle. Each eye sees a separate image and, when combined, your brain sees the composite image in 3D. Simply assemble the cardboard viewer (or make your own), pop your phone in and open your VR app. If you seek a deluxe experience, there's always Poppy 3D.This retro-looking gadget resembles the View-Master and is more robust than the cardboard option.

https://www.google.com/get/cardboard/