We were nearly ready to break out the tin foil hats when we first ran across news that cardboard may be better at protecting your noggin than the polystyrene that's currently en vogue in helmets. Upon closer inspection, it turns out the corrugated paper product actually makes a fine impact absorber.
The technology is called Kranium, and it uses interlocking ribs made from cardboard housed under a stiff plastic shell. Since the cardboard is easily manufactured and cut to shape, custom fitment is possible by means of a simple and personalized head-shaped template. This way, the guts can be cut out of a single cardboard sheet and replaced without buying a completely new helmet.
Tests show that these cardboard helmets can withstand four times more impact energy than regular helmets. Just as interestingly, while polystyrene helmets can only take a single impact, these Kranium helmets can reportedly pass testing after five strikes. Read more about the technology at the Kranium site.