I was going to make a 12.5 single block of the D. hour glass for a swap Im in but think Ill make something else then make a whole quilt using the 10" square as in the video and then I wont have to worry about it being exactly 12.5. Thanks for the hints...I tried 12" block to begin with and its gonna be WAY bigger than 12.5 when finished even with all the cuts you make. IF I ever get one figured out Ill post it! I loved the finished quilt in the video!