I also managed to sew a Cooper satchel. I had enough material left over from the messenger bag to piece together all but one side of the lining, so I used a ladybug fabric for the lining. I wouldn't want clothing or housewares in this fabric, but somehow I still love it. Because I was piecing and had to adjust the sizes of some of the pattern pieces and did it all over several weeks, not everything lined up properly, but the bag works and I would rather have a slightly slap-dash bag than fabric sitting around. I didn't buy a single thing for this bag, but altered the pattern to fit what I could scavenge from the stash.
A triumph for me was properly installing the snap closure. I often put the wrong pieces in or line up the sides wrong, but it worked perfectly this time. Hooray!