This lamp is designed for an LED "puck" light like the one shown in the photo. These battery operated lights are about $4 each; simply do a web search for "LED puck light" to find several sources. This blog page tells where you can get wall powered lights that are brighter and that work very well: http://birkbinnard.com/blog/wall-powered-led-lights/.
This is my first LED light design that features holes that let the light out directly. The holes result in some light patterns on surrounding walls, objects, etc. I used dark blue PLA for my print, but I think a lighter, more transparent color would work better. This print took just under 26 hours using a layer height of 0.200 mm and a print speed of 100 mm/sec.
All geometry created with a combination or Grasshopper & Rhino3D