I am going to post instructions for weaving bags like the ones pictured in the previous post, as promised. I've been sat down with my notes and a set of instructions and diagrams which I have used before and adapted and I started typing and it all seemed very long-winded. So I've decided the best way to give you instructions is to weave another myself, take photos, and post those.
So... there will be a little further delay, sorry.
But in the meantime, this link has a great method for cutting plastic bags into strips for weaving, crochet etc.....
Her sea creatures and other creations on flickr are just fabulous.
And here are some other bags I have woven from rags. These were made on a custom-built wooden bag frame but they could also have been woven on a box.