When I was Brand New to quilting, I saw a quilter on Simply Quilts use a kind of "ruler" that is essentially a big square with cutting slits every two inches. You square your fabric and lay this on it and then rotary cut through the slits. I used it once unsuccessfully - it required more coordination than apparently I possess. Perhaps with practice I could master it... Meanwhile, it sits propped behind my cutting table. for 10 years. lol...