So all the Batman fans out there know that if you need Batmans help then you need a bat symbol to get his attention. So lucky for you I have played around with a few ideas and have found a simple and quick solution.
Thin Cardboard such as a cereal box
Black sharpie (Optional)
Access to the internet and printer
A dark room or closet
Step 1: Find a symbol template
So use google to look up picture of bat symbol or bat symbol templates. I found one, tested out a few sizes and printed it just to make sure. Play around with image sizes in a software such as Microsoft Word. I will attach my document to this step if you would like to try any of those.