I say this quite often but in this case it really is true; this IS a design I've been wanting to get right for AGES. Like, literally for as long as I've been doing this 3D design & printing lark.
When I first started I was on a website called Thingiverse, to download some designs which I could use to test out my new 3D printer (the crap hobby one I used to have, not the two profession-grade beauties I have now). One design which a lot of people on there had made, and which I immediately became fascinated with, was a mechanical box where you twisted the surrounding ring and the top opened like an iris. It was called, funnily enough, an Iris Box and ever since then I've wanted to make my own. But I'm the artist in a family of engineers, and I could never quite wrap my head around how to make the bloody thing work if I drew it myself. For the intervening... oh... going on four years now I've been trying off and on to make my own, and FINALLY recently I got the time to sit down, concentrate and really have a proper go at it. And finally... IT WORKS!! So now I know how to make the damned things I'm putting it here so you can make it too!
The box consists of a nice rounded pot-shaped box, onto which the iris mechanism is attached while still leaving the mechanism sufficient space to work. The petals are printed in a different colour to give a nice finish both when the box is closed and also when it's open, when they then resemble the petals of a flower. A sort of techno-based box-shaped flower, kind of like the Borg Queen would have in her space-greenhouse. Or something like that anyway. I've added step by step photos to help with assembly (as it is, as you can probably guess, a little bugger to assemble...)