I wanted a reusable shopping bag (and book bag and whatever bag) that I could clip to my stroller. All my reusable bags have narrow tops that won't hang on my stroller. This one is not only shaped correctly with a wide opening, but has a clip on each side that attaches over the handle. There is also a shoulder strap for carrying it normally. There is a little pocket inside, made out one of the corners that were snipped off when we created the box-bottom shape.
The fabrics are two coordinating prints in upholstery weight cotton. It's pretty sturdy stuff with a canvas type feel. My mom frequents a discount fabric place that has such fabrics for $3 - 6 per yard. We found these and really loved them; at $6/yard they were a really good buy. The clips are made out of some repurposed clips from baby's overalls. I discovered that you can reuse the clips and adjusting rings, but not the buttons, so I bought new buttons.
I'm toying with the idea of making more, which means I need to transfer the notes we made as we went to something I'll be able to decipher later (and do it now, before I forget what they mean). I'd be interested to know if others are wanting a bag this shape as much as I was!