I make my 31/2 inch hst using 2- 8inch squares sewing corner to corner both ways (1/4 inch each side of pencil line or fold) Then cut from corner to corner both ways and across the center. Just place your ruler making sure its centered. 2-9inch squares will produce 8 - 4 inch hst and two 10inch squares will produce 8 41/2 hst. There is room to square them up with just a sliver taken away.