That was demonstrated at one of our Guild meetings. No pattern required. It works like a Crazy 9 patch but fat quarter size. The person who demo'd it was just winging it. You stack the fat quarters, make two diagonal cuts, two horizontal cuts (not parallel) dividing the fat quarters into 6ths of uneven sizes. The cuts are not parallel to the sides or each other. The first stack remains the same, the second stack has the second fabric on the top and the first fabric on the bottom, the third stack has the third on the top and the second and first on the bottom. And so forth so no two pieces are the same. The pieces were sewn together an pillowcase finished. Sounds like the pattern you saw, they rounded the corners and used fun stitches.