Due to the interest in this subject, I decided to comment...First off, I appreciate the kudos, even if they were not directed my way...no matter.
In answer to Ryan's comment, I want to say I made this prop at the request of my dear friend James Cawley. He provided information and images...I did further research, and found screencaps from Trekcore,(a great source). I used the "grip" area as my primary reference,(provided by another dear friend, the late,great Steve Horch).
When I was about 3/4 done, I found this thread, which I used to merely verify my research. I must say, Ryan, you did get many details very close, however, too bad you missed out on the lens shape, which is shown in the first image in your thread...Your subsequent conjectures seem to be quite a waste of time...the lens is definitely a conical shape.
I am looking forward to your info on the correct switch...