Ben sez, "My 9 year old wanted to make a lightsaber for his monthly science project and Hallowe'en costume so I designed a quick project at his level. I documented the project on my website, and I think it turned out really well. The lightsabers are less than $15 each in parts and only take about an hour or two to assemble."
In this post, I am only showing the base of the lightsaber. It's quite straightforward. I am using four super bright LEDs from Sparkfun, two 220 ohm resistors, a 9V battery, and a switch. For the housing, I cut down some PVC pipe and bought some fittings for the end. The most expensive piece of equipment is the switch at about $4. The entire lightsaber comes in under $10.
As an exercise, I had Devin (the 9 year old) use this website, which generates a circuit and the necessary resistors for a given number of LEDs. It's a good tool and perfect for a child with very little knowledge of Algebra. I'll include a schematic of the LED circuit below. I have also included pictures from throughout the project.