I do not wear a helmet for personal reasons. I am not convinced of their efficacy.

BUT if you do wear helmets – this is one of those things you’ll be interested in. Kranium helmets are built from the same cardboard that make up your shopping boxes.

But what about its impact resistance? The design “absorbs four times more impact energy than the polystyrene equivalent”.

Also they are waterproofed to the same level as your current helmet.

AND they don’t break if you drop it.

Cardboard Bike Helmet Better than Plastic | Gadget Lab | Wired.com.