I have several different sizes of quilting squares to use in squaring up but sometimes they can get quite expensive. On one of the threads someone said that they have theirs cut from plexiglass at Menards and or Lowes. They don't have markings on them but they're a lot cheaper. A 16 1/2" square quilting ruler can run about $35. You can always make the smaller blocks bigger by adding a narrow border. It can make the blocks stand out--like framing a picture--and can really add interest to your quilts. Experiment and find what suits you best.