Today, my son asked if he could make a Vampire costume. I said no. The he asked if he could make a Vampire Bat costume, which was deemed acceptable. So, he made himself a mask, but he wanted wings, too.
This is how you make Vampire Bat wings:
First, google Vampire Bats, to find out where the wings need to be attached. Then take the wing, er, ARM-span measurement of the wingless bat in question, and also measure him from shoulder to knee.
Lay out a large piece of brown fabric, and fold. Use tailor's chalk to trace a batwing shape, using the previously acquired measurements:
Last step: Revel in the awesomeness of being someone who can whip up a pair of bat wings on request.