A friend of mine wanted me to print out this ghost ( http://www.thingiverse.com/thing:426237 ) and also wanted it to light up. so with some time on tinkercad i was able to make a led holder from a old LED computer fan i had laying around. If you have one and want to try your hand at crafting, this is a great project.

First: you need to find a computer fan that you dont want anymore and have the 4 LEDs on it. Take it apart and keep the circuit board and 4 Leds. unsolder the motor's windings off the board, there should be four posts that hold it on.
Second: print out the LED holder and glue the Battery tray to the flat side of the ring circuit board holder. put the circuit board on and glues the Leds into the holder.
Third: I bent a paperclip going through the bottom of the battery compartment and into a circle (so it will make contact with the watch batteries that we will be using) also glue a straight section of paper clip for the contact on the other side of the batteries.
Fourth: soldering, you need to find a slide switch that will be installed into the back of your Ghost's eye, next you need to cut away at the back cap of the Eye to make room for the switch, after that solder all your connections to make a full circuit.
I have also included a defuser to soften the Leds.
Please leave comments if you have any questions.