Mirrorshades is a hardware & software platform which allows its user to observe & move around their real environment whilst wearing a wide field of view, stereoscopic 3D, head mounted display which allows them to alternatively view a virtual reality environment from the equivalent vantage point. This is achieved by combination of a head-tracking HMD, webcams, an indoor positioning system & a 3D game engine, into a mobile parallel reality interface.
Mirrorshades is a Unity application that combines an Oculus Rift DK1 with the IndoorAtlas indoor positiong system. For the IndoorAtlas integration see here & for the 3D printed camera clips see here. For more information on the Mirrorshades project, including photos & videos of it in action, take a look at the blog posts here.