I built this trailer to use on my recent ride down the C&O Canal Towpath. The trail is 184.5 miles and runs along (you guessed it!) the C&O Canal, from Cumberland, MD, to Washington, DC. For the most part, the trail is hard packed dirt, although there are places where it's mulch, crushed rock and even paved in a spot or two. I decided to build this after having gone online and found that, while two-wheeled trailers would work, single-wheeled ones are recommended. I looked at buying one, but at ~$325, I didn't look too long.
That's when I decided I could do better. I think I did...what do you think?
I wasn't sure how to go about building it and thought of a couple different ways to do so. PVC was considered, as was copper tubing, but I finally settled on electrical conduit after seeing I could get a 10' length for $2.50! I settled on brazing the pieces together after perusing the conduit connectors and realizing they probably weren't going to be strong enough. The only problem with brazing was that I had no idea how to go about it. (Sure, I learned in 8th grade shop, but that was ages ago!) I did some searching on the web and finally decided to just go for it. In the end I found out it wasn't that difficult (looking at the trailer, you can tell which joints were brazed early in the project and which were done last -- the learning curve isn't' that steep).
Excluding tools, this can be made for less than $20. What you do with the savings (~$300) is up to you.