the other thing to bear in mind is the complexity of an iris mechanism versue a standard extrusion/guillotine approach.
Three bladee, some complex gearing.
Lot to go wrong - particularly if it's being run for long periods.

Also bear in mind that 3d metal printing is EXPENSIVE !
Whereas a tube with guillotine is pretty cheap and easy to make.
Okay so you need to change out the tube to change the diameter of the sample being sliced - and I can see where an iris would be of benefit there.

I like the idea but can's see how to make it work. If the blades were all on the same plane, then they would blunt each other, ending up in a smush rather than a cut.

There is a compnay that specialises in tiny metal printed widgets who might be able to make something- wouldn't hurt to ask. Now I just need to try and remember who the hell they are !

Well that's annoying - they were at the tct in 2017 - and I did notm,ention the company name in my thread :-(
Guess I'll have to go though the last couple of years of acquired leaflets.

Actually kjust looked through the show guides :-)

Digital metal are the chaps !
https://digitalmetal.tech/
have a chat with them