i have always made my own quilting templates and pattern templates. i learned from books years ago. i used the double bladed exacto knife because of the even spacing between the two edges od the opening. sometimes i goof and don't get my bridges right, but i have figured out a fix for when that happens. to use the exacto knif i "drag" the points of the blades slowly & firmly w the straight edge of the blade almost touching the template material (usually the new heavy multibag cereal boxes like found in costco). i have never used hot knife to cut plastic, didn't seem a good thing to stink up the house w melting plastic. but whatever technique you try, it takes patience & practice.