If you look at the plastic Logicoma toys, you will see that the "turret" is pretty detailed -- it has all sorts of bolts, handles, grooves, etc. Mine is smooth, because it's just an acrylic ball. But I do plan on adding all those details, eventually. I decided to start with the eye socket, because I have a theory about how to make it, and I want to test it.
Since the eye hole in the acrylic ball is cut by hand so that the eye fits in it, I don't know the exact dimensions. So I just placed it against a piece of acrylic and traced with a pen. Then just added the details.
Next, some dremeling. Who needs a laser cutter. It's maybe not perfect, but it's cheap and fast.
Then, I placed the soon-to-be eye socket in a metal ball that I had lying around (it was a box of chocolates for Christmas or something like that) and placed it in an oven. When the acrylic softened, it got this nice covex shape. I adjusted the "ears" manually a little (careful, hot!), and got something that fits on my acrylic ball just right (also drilled the holes):
Next, I drilled corresponding holes in the ball and used the rest of my plastic bolts to secure it in place.
It's not exactly as in the movies, but I think it's close enough.