Anyone who has watched Star Wars knows what an awesome weapon the light saber is. Now you can make a mini version using a flash light from harbor freight http://www.harborfreight.com/3-12-in-9-led-mini-flashlight-69052.html This two piece design allows you to change the color of the light to the one of your choosing.

The collar doesn't need to have any certain infill or shells. The light will need to be printed with a very low infill (close to 0%) to allow the light to shine through. Because of this, be careful with it if you print it with a low number of shells. Best option would be to find some translucent material in the color that you want.