I used Quoth the Raven to decorate my plain Sunset cardstock.
Sew your bottom bat on upside down - my last one wanted to flip, because there was no weight on the end.
Lay your bats (or spiders or owls) out on the floor in a pattern you like before sewing.
Space the thread between bats at different lengths.
I used a thick piece of Styrofoam I had in the garage to keep the paper off the door and let the bats float. (You can 'cut' Styrofoam with dental floss, in a sawing motion.) This I attached to the door with the pull off sticky tabs for hanging posters and such. A small box would work as well.