This is my DIY EMF Detector.
It works pretty good. But I haven't found any ghosts :/
It's an Arduino/Atmel inside, some wires, some leds.
If you want to build your own, I've written some information + BOM onto my website:
https://flazer.com/blog/11/emf-detector-lets-hunt-some-ghosts
The author marked this model as their own original creation. Imported from Thingiverse.