This is great, and I have the pieces required. The hitch will be trouble for me, though, since I can't make custom pieces like you have. I basically have a hacksaw, and then I'll be taking the pieces to someone else to weld them for me (at a cost). I'll be using road-sign angle iron for the frame, like BossCat did.

Speaking of BossCat's design (http://www.bikeforums.net/showpost.p...&postcount=221) do single-wheel trailer need to be hinged in the vertical plane like that? From what I can see of commercial trailers like that, they're not - or am I wrong there?

I think for a hitch I'll need to make something to clamp onto the chainstay on either side.

I will be using this for my courier business and so hopefully I can make it look as sleek as possible!

I'll see how I get on, not sure if it will all work really. I'm sure I'd be better off just buying one, but I'd feel uncomfortable doing that.