There are many examples of good home built bike trailers on the web. Most use aluminum tubing for the frame although I did see one made of bamboo. The approach I took was to recycle discarded aluminium crutches and kids bikes both easily found at thrift stores.

The biggest expense was for the hitch. I went with a proven design by Burley. This cargo trailer has been in use since 2008 and it works well.

The second attempt uses a single folding crutch and a shock absorber from a kid's bike. This design is still in the testing phase.

The water-proof bags are made by Seal Line. The hitch is part Burley and part another crutch.