When I have made templates like this I make a couple of paper copies. I cut it out, place it on the fabric as indicated for folds and straight of grain then lay my regular ruler over it so it is lined up with the edge of the paper template and cut with the rotary cutter. It works well but sometimes you end up shaving a sliver off of the paper so that is why I make a couple of copies. I have also done this with template plastic but once I realized the paper works just as well I use paper.