After four years of tinkering based on the principles of origami, Israeli amateur inventor and bike freak Izhar Gafni has crafted the greenest transportation ever - a $20 bike made of recycled packaging cardboard, with recycled rubber wheels, treated with non-toxics to render it immune to both water and fire. Production is slated to begin soon, with kids' bikes and wheelchairs right behind. The target audience is rural areas in developing countries. 

Izhar cardboard bike project from Giora Kariv on Vimeo.