This is a simple mechanical iris designed to be 3D printed quickly.
To make your own, you need to print 1 base, 1 ring, 5 blades, and 5 pins. The pins may need to be rotated - they are designed to be printed with the large diameter at the base.
This is a work in progress with the improvements planned to reduce friction and ease assembly. It was designed to be thin to speed printing, but this can make it hard to grip and actuate, especially on printers that produce a rougher surface finish.
UPDATE: The 0.25 mm tolerance in the .stl files worked well on Tinkerine DittoPro, not so well on a Prusa I3. There is a parameter in the Fusion 360 file that can be changed to suit your printer.
Note: Photos show first prototype
DittoPro, Not Ditto +
Did PLA @ 220C, 50 mm/s