Visors can be made in a many different ways, form glasses lenses, plexiglass and windowtint, motercycle visors, vacuum formed plastic and dyed, and many more. It all depends on your resources and how complicated the shape is. If the visor/eves are one way mirrored, it may be hard to get a light to shine through. You could try using an LED hidden outside the visor, or use a fabric to look out of that the led is also behind. Bill Daran from the punished props YouTube channel has a skyrim draugher that may give you an idea. Could you explain your idea a little further on how you want it to end up looking?