I've been learning a lot about 3D printing lately (and expecting @danidee to teach me more) and was super excited to come across this amazing design!
A french company put together what you need to 3D print your very own light saber! You'll need more than 20 interlocking pieces, so you should be skilled with your printer before giving this one a go, but if it seems like something you want to try, you can find the design details on Thingverse! (http://www.thingiverse.com/thing:572485)
And, this one is completely customizable, so get creative :)