Not what you're asking, I know, but you could visit https://www.payloadbay.com/page-Tools.html and print one on paper, glue it to a foam board from a hobby store, cut with a matte knife, and voila. I've done all of my rockets this way, from 2.6" tubes to 8" FG tubes.
I use the 1" thick foamular board. You can buy it from Home Depot for $6. Comes in a handy 2'x2' sheet. Super rigid, but easy to cut with a utility knife. It's thick enough to not warp or bend when using it as a fin guide. Good stuff. I used it with my 8" diam. rocket with 7" fin semispans.