Gonna sound crazy - but I use 12" vinyl floor tiles for templates - they are easy to cut with scissors or knives. They are heavy enough to hold the material flat and are easy to rotary cut around or trace. If any of the paper backing doesn't quite cover the glue area, just dust it with talcum powder and problem solved. You can cut out a section in the middle so you can see the material and place it exactly where you want it.