I have to say right up front: these bags are ADDICTIVE!
I decided not to make the assigned size, which was just like a paper grocery bag. I needed a bag to carry my boxes of accessories and supplies back and forth to class. So I altered the placement of folds a little and created an perfect bag to do the job.
I actually hate big bags, but this one has to be large. It's much larger than it looks in this photo.
Box of serger feet in the bag
Lower band forms pockets on the outside. (I don't happen to think I'd ever use OUTSIDE pockets, but it's attractive.)
I used fabric I had made my mother-in-law a dress from back in the 1970's. (She'd be pleased! And my girls like it.)