I got mine at Michael's Arts n Crafts.
Frisket film is great stuff, but solvent base paints have to be sprayed on nearly dry or they will attack the adhesive and let the film lift. I used it with Model Master enamels on my Jenny to do the insignia, but very carefully. It was excellent for tracing out the masks for the lettering.
Mine is Grafix P/N KLM912-12N Low Tack, 12 9x12 sheets in a package. Lots of places on line that carry it.
John Witt