Small Mechanical Iris for a Custom Sonic Screwdriver

I have been constructing a custom sonic screwdriver based upon the 11th (current) Dr. from the T.V. show  Dr. Who.  I decided to add a mechanical iris embedded in the pommel as a feature.  So here are a few pics of the construction and finished pommel for the sonic screwdriver.

Dimensions.
The cam is 20mm in diameter with a 10mm aperture.  It has eight leaves that close to approximately 2mm

The inspiration was from the timepiece iris.

Thank you for looking.