Remember that sheet-metal bike frame that I thought was so fugly?
Dave H sent me this link. This is a bike made of recycled cardboard. It cost $9 in parts (and who-knows-how-much in experience and technical knowledge). From the article:
Bike enthusiast and designer Izhar Gafni built a functioning bicycle out of cardboard...Gafni ran his idea by some engineers who told him to give up the dream, that it was impossible. He tried it anyway. The result is an attractive, working bike that costs as little as $9 to make. Of course, that price tag doesn't include the immense amount of R&D time Gafni put into it.
The bike went through a tremendous amount of prototyping and tweaking. The finished piece is dipped in a coating material that gives it a shiny outer shell and protects the material from the elements. You wouldn't know it was cardboard just by looking at it.
There's video that Blogger wouldn't let me link to at the original article.