One of my goals for next year is to get really good at carpentry and make cool stuff like this DIY plywood bicycle. That is cool!
The part of the design I liked was that the top and bottom parts of the frame are like leaf springs separated by the seat tube. I thought that having a suspension system integrated into the frame was a really cool idea. Ideally vibrations and bumps would be absorbed into the frame and returned back to the wheels, without making the frame too bouncy. The frame I built consists of plywood, fiberglass, epoxy, and even paper, so there is no welding required.