Print our half-bat template; then fold a piece of thick black paper down the middle, place the template on the fold, and trace. Cut out, and unfold. Use a bone folder to crease wings (and fold opposite the direction of body fold).
Poke holes in the bat for monofilament: in the tail for an upside-down bat, in the wings and head for one that's right side up. Hang from ceiling with painters' tape or removable hooks.