Use A Telescopic Snoot For Film Noir Effects
the Film Noir snoot is a telescopic snoot that has a built-in slot for GOBOs which create film noir effects. I suspect that its prime material is cereal box cardboard fitted with black straws for slides and stoppers.
Here are a few pictures of the device followed by their projected patterns:
You can read more about how this creature came to be on Peter's Blog (machine translated)