To Stephen L.
I would surmise the use of Optivisors is to help us modelers in the correct placement of tiny plastic and photoetch parts, especially in 1:72 scale, to which I find myself turning to more and more due to lack of shelf space.
To Neil E
Ah, the humor of you Aussies. Gotta love it, mate. You should write a book entitled: "The Humor of Modeling", or something similar. Could make a lot of Samolians, ya know?