the silicone pressing sheets specifically made for fusible applique protects your work surface from getting any fusible on it- allows you to build appliques- then when cool peel them off the sheet & place them onto the background fabric- I've done lots of Celtic knot & stained glass applique- I've never needed my pressing sheet for that- I lightly trace my design onto the background fabric- then place the fusible bias tape along the lines- pressing as I go- there is no danger of any fusible getting on anything it shouldn't ..I tried a Mylar template sheet once- it did not go so good- made a mess of the Mylar- if you do a lot of applique a pressing sheet does come in very handy- you could order one from Joannes on line- or Nancy's Notions, Keepsake Quilting, Connecting Threads, Hobby Lobby, Fon's & Porters love of quilting, Piece of Cake Quilting and many more- places carry them- I bought mine from my local quilt shop 8 or 9 years ago it is a fon's & porter one