I made a smaller one. You can really make any size. I ended up making 2 1/2" blocks. on the border if you are talking the border fabric that is incorporated with the pinwheels, (like my beige fabric) that needs to be the same sizes as your original blocks. If you are talking about a border as in the finish it up, it can be anything you want it to.
I was just playing and wanted to try this.