Lucy...hope you have fun cutting it.
I guess if you use the same door color...just a bit darker...it seems as part of the door.
I mean...a white door >>> a light gray vinyl base layer + a dark grey vinyl top layer ( monster's pupils)...and perhaps a "glow-in-the-dark" vinyl irises....lol
DGM-Base layer: HERE
DGM- Middle layer: HERE
DGM-Top layer: HERE