I would buy the pattern.
Glue the pattern on template plastic.
Cut the pieces out. I would use the rotary cutter along with a quilters acrylic ruler to keep the edges straight.
Then use that for my templates. I would also put the sandpsper dots on the plastic to help minimize slipping.
I have rotary cut along the plastic successfully. I just needed to pay attention to cut beside the plasic and not tthrough it.