You might want to consider doing 8 at a time HSTs. I am not sure what size your finished HST is supposed to be but if you are shooting for a 4 1/2 inch HST (4 inch finished) you would start out with a 10 inch square. Layer cakes work great for this. You will end up with eight - 4 1/2 inch HSTs with only a few seams. Just look up any video on how to do that. Your ruler can cut these squares and you can also square them up with the same ruler. Enjoy the process!