So I did a quick piece of concept art on a photo of the actress to make sure we were on the same page.
Perhaps you recognize the "eye" as a slightly modified version of the logo for a product by a very...err...powerful company.
I then molded and cast (alginate and plaster of paris, respectively) the area of her face I'd need to work with, since the piece would have to be an exact fit. You can see where I pencilled out where I thought I would do the sculpt. That changed a bit once I got in there in three dimensions.
Don't sculpt in white clay. You can't see what you're doing. I don't know why I bought it. That's just some generic brand Sculpey oven bake clay with a glass mancala bead for the "lens." Because I only had a few days for the project, I wanted to do as little molding and casting as possible, so this would actually become the prosthetic, hence the Sculpey.
What you don't see is that there are two aluminum wires running through the length of the sculpt inside to give it extra strength and that I stuffed aluminum foil in there so that there would be a hollow area around her eye, allowing her to keep her eye open and keeping the piece as light as possible.
It's very difficult to sculpt pristine, machined looking forms, especially with a clay that's soft and rubbery like this, but once it was baked solid, I took a fine grit sandpaper to it, which cleaned things up a little.
Below you see the piece painted and glued on with Pros-Aid. I'd like to have had a little more time to finesse it all around, but it was a fun project. Despite all the corner-cutting, I think it turned out fairly well.