It is a acrylic glass, witch is illuminated by an LED. You can engrave something and tape it everywhere you want.
I don't know, if somebody has had allready the same idear. I like this projekt and it should take not more than fife minutes to finish it up.
It is inspired by the cool work of the Graffiti Research LabGraffiti Research Lab.
Step 1: Cut the Acrylic Glass
Step 2: Drilling the Holes
It should even be possible to place two LEDs in the plate, if the light is not enough for you.
Step 3: Placing the Components
Step 4: Engrave Your Message
Now your done. Take the LED Patchie with your message and place it somewhere. You can tape it or build magnets into it. Hope you have fun with it.
Update: Pixelrider says in the comments:
The fun part is that you don't have to engrave your message - simply write it with a marker pen - especially those UV-sensitive - and use blue/UV LED ;)
I think, that is a gread idea because, it makes it more easy.