It’s not convenient for regular people like us to call for Batman’s help. You need a high rooftop, then you have to make a large spotlight that will call the Caped Crusader. Then, that spotlight takes a lot of power. Your electric bill is going to be sky high. And who wants to climb up to the roof every time you need Batman anyway? Here is a simpler way to contact Bats.
All you have to do is place this 3D printed lens designed by Dalpek over your phone’s flash and it will cast the Bat Signal wherever you point it.
If you want to summon the Dark Knight you can print one out for free using the plans on Thingiverse. Or if you want, you can buy one already made for $6(USD). Pretty cool.