Stainless Steel: What’s happening here?

Hi, I’m Nancy, the Product Lead for Materials and Content at Shapeways. I know maybe some of you are confused and frustrated with the Stainless Steel design rules,
and the disappointing rejection notices you get regarding wall
thickness and other violation of design rules. I’d like to take some
time and update you on what we are doing at Shapeways to address this.                                                      


First, I’d like to recap some of the important design rules..

Basically, the way I think of it–it’s less about the precise number of millimeters and a precise ratio (like 1:2 will work but 1:2.01 will not work, or anything under x millimeter will work and x-.1 millimeter won’t), and more about the question, will it break? The part of the process where a model usually breaks is when the material is in the “Green State.” The way I like to think of it is, if I sculpt this out of wet sand–can I pick it up without it falling apart? Or, if I made this out of really brittle, unbaked clay–can I pick it up without it breaking?

While visiting our suppliers, I took a quick video of me playing with the Stainless Steel in the Green State (a fragile stage in the middle of the process). See how fragile and easily breakable this is? And this piece is actually 3 mm or over!

The current version of our Stainless Steel design rules can be found here, in detail. There’s also a blog post
that describes some of the nuances. But more importantly, here’s what
we’re cooking up to deal with the confusion over these rules.

So what are we doing so far? Well, Shapeways is currently working to…

Define a clearer set of design rules
The first thing we are doing (we’re actually in the middle of this
process right now), is working with our printing facility to add some
clarity to the design rules. There are many things that are indeed
printable that have walls under 3 mm. Currently, the draft of rules we
are using states that no parts are allowable under 3 mm, but in reality
there are exceptions. We are trying to formalize those exceptions into
design rules to give you guys freedom to make more cool stuff.

Consolidate design rules and documentation
Another stream of work is to consolidate the design rule communication.
Currently, there are rules posted on blogs, others on static
pages–basically, they are a bit scattered in various areas and not too
easy to find. To that end, I am working with Ben and Ana to revamp the
Design Rules section of our website. We want to consolidate all the
design rules so that there is a golden source that will get updated
when there are changes, and so that there’s one place to go to for easy
to understand rules.

We also got feedback that more examples would be helpful, so we hope to
build up an examples database as well as part of this new Design Rule

Notify rejections sooner and with more details
We are aiming to give you guys feedback on your models as soon as we
can. There is an automagic check when you upload your files that
captures some of the errors. Then there’s a manual check that looks
more closely at your models. This is why sometimes you would get a
“success!” message followed by a “rejection” message. We are working to
get you feedback sooner, and with more detailed explanations of why
your model is not printable. Or at least, get you more help in
understanding the rejection e-mails if you don’t understand something.

Create a better feedback process
Another point of feedback that I’m thinking a lot about is the
communication element of this, and effective ways to manage design rule
changes. You guys are quite adept at sending pieces that push the
boundaries of 3D printing, which is awesome! I’m sure even the best
design rules will not capture all the use cases. To that end, we are
thinking of ways to set up on our end a better process to review
rejections we get from our suppliers on a more regular basis, have a
better process to spot trends and quickly work with our suppliers to
either push the boundaries of what they will produce or modifying (and
communicating!) the design rules to you guys. This feedback process
will help us rapidly iterate the rules and test new boundaries at the
same time. It will help ensure that we keep our education materials
updated and thorough as well!

Well Nancy, what can I do to help?
Actually, having a bunch of examples of models that have failed, and
models that are under 3 mm wall but still succeeded in printing would
help us clarify the rules. If you have any models, you wouldn’t mind we
use in our discussions, please let me know at

So there you have it. We are approaching this problem through a variety
of different tacks. If you have any more ideas, please do let us know!



Image of Steel Rule(er) 10 / Steve Dorsey /


  1. Benno

    Hi Nancy!

    Thank you for your message, it clears up a lot. I was wondering, do you know which 3D modelling software can perform wall thickness tests? I’d like to test my models on my own computer.

    - Benno

    1. nancyliang

      Hi Benno, this is actually a very interesting problem for us. There isn’t a software on the market that reliably checks wall thickness automatically. We would like it so that Shapeways will analyze these things for you right when you upload! Currently, there are a few software packages that does this, but to my knowledge they are mainly for industrial or mechanical parts. A lot of our designs are organic and confuses these programs, making them unreliable.

      I did find a thread on the forum from 2009 that discusses this: — one member mentioned that he/she was developing a script for Blender (free 3D modeling and animation software). Maybe follow up with that user to see?

      If anybody else here has any leads on a reliable wall thickness detection software, please let us know! Likewise, I’ll keep you guys posted on anything I hear of.

    2. Paul King

      It’s not automatic, but NetFabb Studio (the basic free version) has a measuring system that includes wall thickness measurements.

      @Nancey… Great news, I’ll be able to get back to designing for stainless with confidence soon :)

    3. Ralph van den Borst

      Hi Benno,

      Please have a look a this:

      Here you can read how the measure wall thickness.

      Always keep this in mind while designing:

      White Strong & Flexible = 0.7 mm But we advise you to use,at least 1 or 2 mm, depending on the size of the area.
      White, Transparent & Black detail = 1 mm,
      Gray Robust = 1 mm,
      Stainless Steel = 3 mm,
      Full Color Sandstone = 3 mm,
      Milky White Matte Glass = 3 mm,
      Alumide = 1.5 mm

      Hope this helps you out a bit.

  2. Ana Hevesi

    That’s good to hear, Paul. Giving you guys what you need so you can confidently and reliably design in metal is probably the most important factor in all this. We’ll continue to keep everyone informed as the solutions progress. :)

  3. Chorlton

    Assuming that there wasn’t an issue with picking up the component after printing what is the minimum wall thickness that could be printed? I have seen ceramic components with very thin wall thicknesses but in a honeycomb structure which although very thin will not break as easily when handled.

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