I'm working on my trailer since 2004. Became kind of a hobby. My first design started out with a two wheeler similar to the Yak-design. But the ride wasn't satisfying. So I changed my design and that is the state where I am as of now. It's mostly made from soft steel tubing and some round steel tubing from an old hammock I had laying around. I plan to add a top to it made from aluminum frame and tarp.
The trailer is meant to be a carrier for some NICad batteries (in the sub-floor) to run my electric assisted bike. A project I will start once the trailer is complete.