Sew carefully with 1/4 inch seams and watch the stretch. The bad new is......the bias edges stretch.....the good news is......the stretch helps to make the pieces line up well. The other tricky part is dividing it into 3 equal sections for cutting. My block ended up being a smidge over inner measurement but I used 2 1/8 with a smidge over the 1/8 mark on my ruler to do the last 9 patch cuts.
It came out quite nice and I will make a few more until the pale yellow background from my stash runs out. Hopefully it will be an even number of blocks. On the final 2 seams when sewing the 9 patch together, I pressed them open as there were a lot of seam allowances. Here's what it looks like.