I have used this method for years on quilt patterns that have lots of small squares - like Double Irish Chain for instance - made one once with over 2700 squares - ever since the "watercolor quilt" craze. I don't buy the kind with the grid - it's too expensive for my purse. I buy the Pellon very lightweight fusible - and lay it on my fold up cardboard mat with the 1" grid. I iron right on that as well - with my hand held mini iron - just enough to tack down the squares before taking it to my ironing board. I find it to be a great time saver - and it really helps with corner and point accuracy. (did another with more than 400 HSTs)