One cardboard box, white paper, tape, a permanent marker and some high lighter markers, a box cutter or some kind of a knife, a bright LED light like one of those spinning pumpkin lights (they work great)..a little imagination...
And you've got yourself a nice creepy face. I used a cat's of course, you can probably draw a pumpkin, skull, ghost face whatever you want. Here's the image in the day light:
