This is pretty self-explanatory.
Can you build a real lightsaber? Well....NO. I mean not at least by today's standards.... IN THEORY tho, anything is possible. Watch this Michio Kaku video, it is delightful. :-)
In it he explores the realistic obstacles facing the modern-day construction for a weapon of elegance (I don't know about the 'civilized time' part though....) such as this. The end product is a drastically visual difference to what you'd expect but it fits the bill as far as form and function go.
Since this article seems to be lacking in the substance department I think I will add another video the mix along the same lines.....
and for comedic effect.....can't forget tha haters.