The Bat-Signal is one of the iconic parts of Batman, up there with Alfred, Batarangs and dead parents.
Now, thanks to this design by 3DNG that was uploaded to Pinshape, you can have a Bat-Signal right in your pocket.
As far as concepts go, this one is straightforward. The print is made to slip onto a phone with an exposed end where your flash emits from. Turn on your torch and the light will shine through one of three Batman logos and project it onto a wall (or clouds if they’re really, really low).