What about how you take a square of each color placed right sides together and sew 1/4 inch all around the outside of the the square and then cut down the middle corner to corner making and x? What size of square do you need to make the resulting 4 HSTs if you want a 10 1/2 inch or a 8 1/2 inch ? I saw this on YouTube but could figure out the size of the square. Thank you in and advance for the help.