I have read a few posts about using th blue board insulation to create a mold for stepping stones. (Thank you for posting your documents with instructions!!)
I am a little "fuzzy" on part of the process. After carving out your design, (letters/shapes/etc), is a square form set on top of the blue board to make the sides? I'm a very visual person and would LOVE to see a picture of the concrete in its form.