I know this example with the head and a camera.
But is there an easier way to do this?
Explanation: If you have two or more reflecting objects, you see each
object mirrored in the other object. And if you have an animated scene,
the reflections should animate too. The Shiny Metals Shader or Glass Shader
of the library only shows static pictures. Yes, it should be possible to
use a camera in each object to show the other object, but this is like shooting
sparrows with cannons ( = to break a fly on a wheel
)