2 Any color LED's you want
A box with a lid with a hole in its middle
Step 1: Making the Light System
Step 2: Finishing the Product
Take a piece of paper and roll it into a tube and cut a small rectangle for the switch and then put the lighting system in with the LED in the middle and the switch in the rectangle hole.
Turn the switch on and voila your own cheap lightsaber.
You can use any color LED you like.