I made the QST squares two different ways, since I was stashbusting. I had lots of odd-sized scraps to use, so I tried the 3.5" squares cut in fourths. For the smaller pieces, and the 1.5" strips, I used a Fons and Porter ruler meant for making flying geese, but it had the same markings as the ruler Bonnie used. I discovered I'm not very good with that method, as those triangles were slightly smaller than the ones I made starting with a square.
I'm doing mine in green, brown, blue, and neutral, as those are the colors I need to use up in my stash.
I've made 42 of the string blocks so far; I also recommend trimming to size AFTER you remove the paper. I've made over 2,000 string blocks this past year, so I speak from experience - your blocks expand a bit after the paper is removed.