The duffel bag is completed. It's pretty awesome, if I say so myself. And my husband thought it was awesome - and when was I making him one?
You can't see it in these photos, but there is a row of the webbing on the bottom of the back, and about the middle of the curved bottom front. That's just to give it additional support.
The fabric is a nylon canvas - waterproof - I tested it in the sink. It really is.
This was a fun project and I'm glad my friends on twitter thought of me when it came up.