To change the ambiance / color, add a drop of translucent paint to the end of the fiber. When you add it to the end of the fiber that is inserted into the Lamplighter, make sure the paint is dry prior to inserting the fiber into the Lamplighter box.
See the video on how to do this. To create an old world look, I use the Tamiya X-26 Orange Translucent paint, however, you may use whatever paint you like or even a colored marker.