It is adapted from the Chubby Charmer pattern by Quilts Illustrated. I have made this one smaller and used strips instead of charms.
I also added a covered bottom to mine. After trying many different options, I have found that the best material to use for the bottom base is a plastic corrugated lawn sign - the kind that organizations use to temporarily advertise upcoming events or politicians use before elections. They are more than happy to let you have those signs once the event has past. The plastic easily cuts with an old rotary blade or an exacto knife.
I especially love this tote because it has snaps on the side which allow you to make the bag smaller,
or open the snaps and make the bag larger.
I now have a gift ready when I need one. This may become my "go to" pattern for the remaining monochromatic challenges. I just can't keep making quilts that end up being UFOs, like the yellow:
and the green challenges: