While searching around for round robin ideas for my house quilt, I found this very interesting border idea.  It's made from HST along the lines of some other quilts we've made here, where it gives the illusion of a barber pole.  Pretty cool for a border.  The math might be a little tricky, but still a fun result.

depending on how you piece that you could make it from just triangles so could scale it to any size to fill the space. Also a piecer border could be used to make the math work better.