“Okay, I can show you how to make a slow eye and then you can improve it when you've gotten better materials — all of mine are in the eyes I'm using,” he says, waving at the ex-birds.

He takes some glass and something black from somewhere, and hands her half the black stuff. Presumably he expects her to claim it easily.

“You need something black to block out the light that's not coming in through the lens, and it'll also do for a slow sensor.”

He makes a hollow cylinder with a hole in one end and the other end solid out of the black stuff, and lets her look at the shape of it.