Yes, it is as cool as it sounds.
You can actually use this foam LED lightsaber to battle with someone. Not only does the lightsaber glow by using LED lighting, it also produces sound. (No more mouth sound effects needed!)
This is a kickstarter at the moment, but it's already been backed with 22 days to go. The prices vary, but essentially start at $170.
Here's a lab video showing the density of the lightsaber:
Here's a video showing how you can customize the lightsaber by using a smartphone: