Writing and painting with light. This idea is not a new one:
You just take a camera, switch it to longtime exposure and paint with a flashlight, or LED, some characters in front of it. This works properly, if you are able to draw. I'm not.
So I just stood by admiring those people, but knew I will never be able to do this. Two years ago, while I visited the 30c3 (Chaos Computer Congress), there were some guys from Blinkinlabs. They sold some bags full LED stripes. I bought on e myself anf found out, that you are able to blink own images with it. But unfortunately mine broke after some days of testing. They are not (very) waterproof...

The idea to build an EMF-Detector came while i fucked up my last project partially. While i was soldering the pcb i did a mistake while connecting a wire. This gave me a broken signal of a buttonstate (switching from 0 to 1) switching back and forth. I fixed that, but wanted to know exactly why this happens.

Result: When you don't connect the input of the controller to ground, you are not able to set a solid state and the µController starts to interpret everything what he gets. In this case it reads electromagnetic fields. So why not digging further into this and build a gauge to have a look on which devices are having a nice electromagnetic party?