I have not used it, but a friend uses the Deb Tucker ruler that does this - can't remember the name. But if you go go Studio180 or key in Deb Tucker rulers, you might be able to find it. She says it uses a little more fabric, then you trim the squares down to size, but she swears by them.....says they come out perfect! If nothing else, maybe you can view Deb Tucker videos for some hints.