A friend bought this beautiful fabric and hired me to make two knitting project bags for her. She had one bag already that I copied, except, at her request, I changed it to a double drawstring and used self-fabric for the drawstring instead of twill tape.
This one has two rectangular pieces, sewn together on three sides, with triangles pressed in and stitched to make a square base. There’s an identical lining of the striped fabric, sewn to the outer in such a way as to make a casing for the drawstrings.
The second bag (not pictured) is a bit smaller, has the stripes going horizontally in its liner, and has a separate circular base.