This is a plug, a.k.a. "kill-key," for a 2.1mm charge port of the kind commonly used in custom-made illuminated sabers. This one has a cap that is more or less identical in size and shape to the greeblie found on the side of the Obi-Wan Kenobi "Revenge of the Sith" lightsaber hilt.
If you plan to use this in a charge port, I strongly recommend that you do not order this item in a metal material! A metal kill-key could cause a short and damaged your saber. I have made this item available in metal only for those who simply want to use it as a cosmetic greeblie, rather than as a functioning kill-key. If you want the cap to be metal, please order my "ROTS Obi-Wan greeblie cap" in metal, and order my "blank kill-key tube" in plastic. The metal cap and plastic tube can then be glued together with epoxy for a safe, good looking kill-key. (It should also be a bit cheaper.) Not that "Alumide," despite the name, is not conductive, and is therefore safe for use as a kill-key. Also note that it should also be possible to electroplate such metal materials as "Stainless Steel."
Also, note that Shapeways printouts are not perfectly smooth. (It's an inherent limitation in current 3D printing technology.) However, the metal materials can be sanded and polished. If you want to sand a plastic item to a smoother finish, keep in mind that in colored plastics (including black), the color is only on the surface, and that if you sand too much, you will expose the white plastic beneath the color surface.