Software Review: Iris Calculator

Art & Sculpture Craft & Design Digital Fabrication
Software Review: Iris Calculator

Software: Iris Calculator, by Matt Arnold

Price: $4.99 monthly or $39.99 yearly

Last year, I found myself obsessing over a new project. I wanted to make a mechanical iris peep-hole for my front door. I worked up a prototype over the course of a month or two and learned a lot of things. One day, I’ll finish the design out and share the whole project, but for now you’ll have to live with this simple preview animation.

During the process of building this mechanical iris, I discovered a fantastic tool for exactly this use. The Iris Calculator by Matt Arnold turned out to be exactly what I needed to tweak my design. Since the software is not free, I thought a review of the software would be a useful thing for those considering paying to use it.

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I started by simply downloading a mechanical iris from Thingiverse, to figure out exactly how it worked. The design was nice and worked pretty well but I really wanted to customize it. Wondering what it would take to do more, or fewer blades, I began research. Designing irises from scratch isn’t insanely complex, but it isn’t particularly fun either. Iris Calculator took the pain away in an instant. I could switch major design choices like number of blades or maximum width in an instant and have a new design. This gave me considerable time savings.

I entered the measurements I wanted and it spit out a DXF file for me. I was able to take this file into CAD and extrapolate the design from there. Ultimately, the cost of the software was almost nothing compared to the time I would have spent re-designing to try different geometries, and I’d highly recommend it to anyone wanting to make their own mechanical iris project. The only caveat is that it only has one style of iris included right now, something that the creator addressed in my interview.


  • Fast iteration of geometries
  • Nice visualization of of the iris opening and closing
  • DXF export comes as full assembly and individual components for easy importing


  • Only one kind of iris included

I talked to Matt Arnold about the software a bit and he shared some back story

I used to work for Wilkes Iris Ltd. — a big iris manufacturer in the UK which had been operating since 1884 — and I’d created the iris calculator as an in-house tool to help me design irises and for the company to be able to produce instant quotes to clients. They used to supply irises to all the big stage lighting companies, like; Martin Professional, Times Square, VariLight, Selecon, Robert Juliat, Clay Paky, etc… There was no references or documentation for iris diaphragm design at Wilkes (it was all stored in people’s heads, and lot of those heads had been and gone over the years). Nothing on Google, and I was surprised when I was told that all they used to do at Wilkes was make cardboard models, and trial & error until they got something that roughly worked!
Ultimately they weren’t interested in using the iris calculator themselves, so when I left I took it with me.
I explained my pros and cons to Matt and was happy to hear his response:
I’d agree with your observations.
The current development road map of the iris calculator includes:
– To add the other iris types: finger, star, slider, and even the barrel – for the old timers ;)
– Slot angle adjustment to change movement handle rotation angle
– Complete set of engineering drawings
– Complete .STL 3D model
– Plus many other improvements…
Matt's free iris on Thingiverse
Matt’s free iris on Thingiverse
I’m very happy to hear that he’ll be adding different types of irises to the tool. He also told me that he shares a basic iris for free on Thingiverse and keeps a Pinterest board full of iris inspiration.
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I get ridiculously excited seeing people make things. I just want to revel in the creativity I see in makers. My favorite thing in the world is sharing a maker's story. email me at hello (at)

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