Current head-mounted augmented reality devices don’t provide a full field-of-view display, which limits their ability to provide fully immersive graphics or even to play movies.

So Matt Kwan, a PhD Candidate in Geospatial Science at RMIT University, in Melbourne, Australia, decided to build his own. How hard could it be? Not very, it turns out, he reports in my20percent.

He put one together using a smartphone (an HTC Desire Z), a baseball cap, a couple of fresnel lenses, a plastic mirror, some mirrored film from an iPhone screen protector, and assorted office supplies.

The smartphone is held in place with a rubber band, and whatever appears on the screen is displayed in the wearer’s field of view. The fresnel lenses are there to push the screen’s perceived distance out to about 50cm, otherwise you’d get serious eye strain.