I, like other people on this forum, really wanted my prints to be illuminated while the printer was operating. I first thought about going the adhesive-backed LED strip route, but thought that they would eventually unstick, which was exactly what happened to gmay3. I bought a cheap Adafruit LED ring that has individual drivers for each LED and its own custom library for programming the properties of each individual LED through the Arduino IDE. It fit perfectly around the J-Head, not at all tight. It might even work on your bulkier hot ends. I ran the power, ground, and data input wires to the back with the rest of the extruder block wires where I then connected it to a perfboard that had an Adafruit 5V Trinket (basically a mini Arduino that costs less than half the price of an Arduino-Mini, just with less pins). I also connected it to a latched switch that had an integrated LED ring so it looks nice and pretty. You can find the link with some pictures and a schematic below. As of 8-31-2014, there aren't any pictures of the actual LED ring in action, just some pictures of the components and assembly. I'll be adding a picture when I return home.

http://www.shawftware.net/2014/08/pr...d-mounted-led/