This lamp combined the Stereoscopic slide viewer elements of my Stereo-Viewer with an earlier lamp design. It can be used to view 3-D slide photographs, or simply as a lamp.
The eye piece was carved out of a block of basswood, with two holes bored through it 2.5 inches apart.
I carved it into shape with a dremel, sand paper, files and a rasp. I added magnifying lenses removed from loupes, and measured their focal distance.
Behind the eyepiece, in the interior of the lamp is the slide holder. It holds the slide at the proper focal distance and diffuses the light from the bulb behind it to backlight the slide.
I had been waiting for the right use for this plug with two finger holes.