Amazon.com: Google 87002823-01 Official Cardboard- 2 Pack, Brown : Cell Phones & Accessories
Google Cardboard 2.0 : 11 Steps - Instructables
Google Cardboard,VR Headsets 3D Box Virtual Reality Glasses with Big Clear 3D Optical Lens and Comfortable Head Strap for All 3-6 Inch Smartphones (Yellow, 1 Pack)
Biconvex Lens Set, Pop-Tech Glass Lens Bi-Convex 34mm Diameter 45mm Focal Length Lens for DIY Google Cardboard VR
Google Cardboard,VR Headsets 3D Box Virtual Reality Glasses with Big Clear 3D Optical Lens and Comfortable Head Strap for All 3-6 Inch Smartphones (Yellow, 1 Pack)
Amazon.com: Google 87002823-01 Official Cardboard- 2 Pack, Brown : Cell Phones & Accessories
Specifications for viewer design - Cardboard Manufacturer Help
DIY: Build your own Google Cardboard VR viewer | Computerworld
What are the lens dimensions for Google Cardboard? Does it need to be biconvex? Is 40mm (25 optic power) the best focal length? What should be its size/diameter? - Quora
Google Cardboard Experiment
Specifications for viewer design - Cardboard Manufacturer Help
Cardware! - Cardboard VR Projects for Android [Book]