I agonized over what design it should have. When I finally decided how I wanted to make it (long bag with boxed corners), I had a heck of a time finding a zipper that would be long enough. I remembered that I could cut down a duvet zipper. Then it took me months before I could find a duvet zipper.
Once I found one, I finally got around to constructing the bag. I decided to quilt the two fabrics before putting in the zipper. I quilted it around the names of the cats.
I then folded the long edges in 1/4" and sandwiched the zipper tape between the layers and sewed the zipper into place. After boxing the corners, I added a handle.
It fit the swift with the bottom screw in all the way.
The bag is completely reversible because rather than leaving an opening in the lining for turning. I turned the bag right side out through one of the handles.
There were several inches of quilted fabric left after I trimmed the bag, so I made a flat zipper pouch. I used double folded fabric over the raw edges on each side.