Cover for our Cargo Trike

I have a lot on my plate right now: trying to keep up with Rebourne, planning for a craft fair (especially hard considering I’m making a bunch of stuff just for this event), trying to organize and make my kids’ Christmas gifts, and trying to work on accessories for our cargo trike.
I’m going to focus on the cargo trike: I want to make a cover for it like this (a Christiania trike, photo from flickr):
I’m trying to figure out what hardware and fabric I’ll need, and where to buy that. Most likely Seattle Fabrics.
I really love this part of the design process, where it’s mostly in my head and ideas, fabrics, hardware solutions, and recycled materials all come into play.