Checkout this cool mechanical iris shutter made of brass and wood. Its main purpose is to be installed with a glass dome on one side while serving as the peephole in a nautical-themed door. This is such a cool idea which can be used in several creativities.
To be able to function well, it requires a little bit of tweaking. The concept is to open and close the aperture by rotating the outer ring. There are many ways by which this iris shutter can be built depending on the type of materials they will use. Incorporating gears in the design is more appropriate. It can also be built entirely out of aluminum.