Lens For Movie Close Ups How Are The Parts Of A Camera Shutter Supported And Made To Slide From The Perimeter To The Center?

How are the parts of a camera shutter supported and made to slide from the perimeter to the center? - lens for movie close ups

An area closed shells of molluscs appears on the other side to the whole circle of the opening of the camera lens covered.
What are the different "shell shaped"? How can I use?
As shells resting on the size of the opening goal and how you came to the edge of the lens aperture when the shutter is clicked? Where to go when opening the shell aperture?
In the science-fiction movies you see the doors that look like windows of the room. Where are the parts when you open the door?