This is an iris mechanism built into a greeting card sized card (5" x 7"). For simplicity and to help keep the thickness low it only has 3 leafs. This particular design does not scale well to more leafs unless it is made much larger. The initial design did have 4 leafs and is built in a way that would allow it to scale to a different number of leafs more easily. If anyone is interested I could upload that as well.
This card has slots in the back that allow you to stick a 2" x 3" photo in the back and reveal it when the iris is opened.
I have this setup for 8.5" x 11" sheets, but if you have a bigger sheet you can combine the two files.
Cut the parts out of a sturdy paper (I use .014" thick card stock) and follow the video instructions here: http://www.youtube.com/watch?v=Wl4Lhaqy89c
Instead of the peel and stick adhesive you can just use any decent paper glue. Elmer's glue works fine, just be careful not to let any into the moving parts of the card.