Either freeform or using a template you've drawn yourself, cut a bat silhouette onto duct tape. Repeat cutting to make a complete bat colony. Tip: I modeled my bat shape off of this simple drawing from <a href="http://www.macaronisoup.com/Songs/October2004.htm">Macaroni Soup</a>. Since duct tape is a thick craft material, know that some of the details of your bat may get lost.
Place the finished bat shape onto a clean Mason jar. Be careful not to leave thumbprints as washing them away will also weaken the duct tape adhesive while leaving them on may clutter up your shadows. Place a small votive candle inside the jar, light and get ready to run as the bats come dancing after you. Tip: Consider putting little red fangs or even cutting them out of your bat for an added scare.