I will show you how to make a ninja mask out of a t-shirt. At the end, it is really cool, but don't walk around carrying a gun in public with the mask on, You look like a terrorist.
P.S. I didn't make this up myself, I just didn't find an instructable about this so I decided to publish it.
Step 1: Getting the t-shirt
To start off the mask, first decide what color you want your mask to be. If you want red, get a red t-shirt, black, black t-shirt...etc. after that, turn the shirt inside out.