The Arduino is great, you can make it do pretty much anything you want.
I wanted a tripwire. This is just the circuit and the code, you can use it for quite a few things, like a trigger for a camera, or you could make it shut down your computer if someone crosses it.
When I have the time, I want to hook it up to an electric airsoft gun with a relay and have it shoot you when you break the beam. I suppose I'll add to the Instructable when that happens.
So let's start!
Step 1: Components Needed
This is what you need for this project:
-Photo resistor (Practically any value will work, the program will just need to be changed slightly)