What is wrong with paper? You could use plastic or mylar but paper is easier to cut. I use freezer paper but many people swear by construction paper or cereal boxes. You can also order the hexagons in paper, plastic or mylar in almost any size from many places on the internet. Patti Shambaugh had some plastic ones with a hole in the middle. She would pin a square of fabric through the hole and baste it around the edges then whip stitch a bunch together. She used a chopstick to pop the template back out.