<p>I posted this to an <a href="https://forums.autodesk.com/t5/meshmixer/can-i-reverse-engineer-a-voronoi-object/td-p/8006487" rel="nofollow noreferrer">Autodesk forum</a>, and a fellow named "MagWeb" proposed the following solution.  I have not tried it yet. </p>

<blockquote>
  <p>A possible workflow depends much on the overall shape of the voronoi
  object:
  If it's convex  all over (like an egg) or convex and planar (like a
  cylinder) e.g:</p>
  
  <ul>
  <li><p>SelectAll (Ctrl+A or Cmd+A on MAC)</p></li>
  <li><p>Run Edit/FitPrimitive and set its PrimitiveType to ConvexHull (CreateNewObjects checked)</p></li>
  <li><p>Run MakeSolid on this hull object and set its SolidType to Accurate. Accurate enables the OffsetDistance slider. Pull it down a bit and hit
  update. You want to get a result intersecting but showing the voronoi
  object. If needed adjust the offset. Finally accept.</p></li>
  <li><p>Now activate both the voronoi and the MakeSolid result and run BooleanUnion</p></li>
  <li><p>Show the FitPrimitive object again (MakeSolid did hide it before) and run MakeSolid again in Accurate mode. Now set a slightly bigger
  offset as you did before. The difference will determine the "lining's"
  thickness. Accept</p></li>
  <li><p>Activate the BoolleanUnion result first and the last MakeSolid result and run BooleanDifference to get a hollow object. You might use
  another intersecting object to bool-off an opening the bottom.</p></li>
  </ul>
  
  <p>Harder but doable with a different workflow on an voronoi object
  owning concave regions...</p>
</blockquote>

<h2>edit</h2>

<p>Having run some trials, I can confirm this works for simple convex objects. If there are concavities, most likely the source shape needs to be chopped into sections each of which can be treated as convex.<br>
 I played around with Meshmixer's "apply pattern" functions with limited success.  I could get a form-fitting pattern shape but with a rather uneven surface. Some fine-tuning of the pattern parameters may help. Note that the new shape tends to be as thick as the original voronoi object, so it may well be better to do something like the following:<br>
1) create a duplicate of the original<br>
2) shrink the duplicate by a few percent<br>
3) align the two objects to a common origin and take the boolean difference to create a thin-wall version of the original.<br>
4) Build the pattern object based on that thinwall object.   </p>

<h3>edit number 2</h3>

<p>I succeeded!  For those who care, I took an open Voronoi glasses case and put a skin inside to protect your glasses.  See <a href="https://www.thingiverse.com/thing:3013220" rel="nofollow noreferrer">this Thingiverse item</a></p>

CC BY-SA 4.0
2018-07-31T12:38:34.353Z
The thing you linked shows up empty, no preview :(
0scar
CC BY-SA 4.0
2018-07-31T13:47:27.280Z
@0scar  Yeah, I don't know what Thingiverse did wrong. I've tried to edit but the STL images don't show.  I'll add an actual photo one of these days.
Carl Witthoft
CC BY-SA 4.0
2018-10-25T13:00:17.613Z
@Trish  Amazingly enough, I found the forum page - now linked in my answer.
Carl Witthoft
CC BY-SA 4.0
2018-05-17T13:46:58.293Z
2018-10-25T12:59:57.090Z
2018-10-25T12:59:57.090Z
Carl Witthoft
<p>Suppose I'm given a shape with a Voronoi pattern, such as <a href="https://www.myminifactory.com/object/3d-print-voronoi-spiral-centerpiece-vase-11900" rel="nofollow noreferrer">this lamp</a>.  I'd like to be able to add a "skin" which covers the complete shape on the inner surface so I could print it with translucent material to produce a more-or-less uniform glow.  Here's an example of what I'd like to end up with: <a href="https://www.myminifactory.com/object/3d-print-voronoi-tea-light-shade-36071" rel="nofollow noreferrer">tea lamp shade</a>.  Any ideas on how to reverse-engineer a Voronoi object? </p>

CC BY-SA 4.0
2018-05-14T12:39:50.913Z
I will rather ask on blender forum or pure 3dGraphics, as this is a very hard question - there are a few google responses when you search for 'reverse voronoi' , but I am not so deep it 3d modeling to suggest anythig.
profesor79
CC BY-SA 4.0
2018-05-14T16:02:27.417Z
I think blender might be the best application to accomplish your objective. With my limited knowledge of the software, I can only envision manually skinning each hole, but there has to be an easier way to accomplish your task than that.
fred_dot_u
CC BY-SA 4.0
2018-05-15T19:04:50.503Z
@carl-witthoft With any program  than can edit your STL file and adding a mesh to the inner surface. Few years ago (18) I was using 3Dmax to create some models and adding meshes to create skins or textures, you can find any tutorial to use it easily.
Fernando Baltazar
CC BY-SA 4.0
2018-05-16T12:46:58.763Z
@FernandoBaltazar thanks for the pointer.  If you could post up a simple example or "steps to follow" as an answer, I'll accept it.
Carl Witthoft
<cad><voronoi>
How to add "skin" to a Voronoi shape?
Carl Witthoft
# How to add "skin" to a Voronoi shape?

(Asked by: username_0 on 2018-05-14)

Suppose I'm given a shape with a Voronoi pattern, such as [this lamp](https://www.myminifactory.com/object/3d-print-voronoi-spiral-centerpiece-vase-11900). I'd like to be able to add a "skin" which covers the complete shape on the inner surface so I could print it with translucent material to produce a more-or-less uniform glow. Here's an example of what I'd like to end up with: [tea lamp shade](https://www.myminifactory.com/object/3d-print-voronoi-tea-light-shade-36071). Any ideas on how to reverse-engineer a Voronoi object?

**Tags:** cad, voronoi

> **Comments:**
> **username_1**: I will rather ask on blender forum or pure 3dGraphics, as this is a very hard question - there are a few google responses when you search for 'reverse voronoi' , but I am not so deep it 3d modeling to suggest anythig.  
> **username_2**: I think blender might be the best application to accomplish your objective. With my limited knowledge of the software, I can only envision manually skinning each hole, but there has to be an easier way to accomplish your task than that.  
> **username_3**: @username_0-username_0 With any program  than can edit your STL file and adding a mesh to the inner surface. Few years ago (18) I was using 3Dmax to create some models and adding meshes to create skins or textures, you can find any tutorial to use it easily.  
> **username_0**: @username_3 thanks for the pointer.  If you could post up a simple example or "steps to follow" as an answer, I'll accept it.  

---

## 1 answers

### Answer by username_0 on 2018-05-17. Score: 4 | Accepted answer

I posted this to an [Autodesk forum](https://forums.autodesk.com/t5/meshmixer/can-i-reverse-engineer-a-voronoi-object/td-p/8006487), and a fellow named "MagWeb" proposed the following solution. I have not tried it yet.

> A possible workflow depends much on the overall shape of the voronoi
> object:
> If it's convex all over (like an egg) or convex and planar (like a
> cylinder) e.g:
>
> * SelectAll (Ctrl+A or Cmd+A on MAC)
> * Run Edit/FitPrimitive and set its PrimitiveType to ConvexHull (CreateNewObjects checked)
> * Run MakeSolid on this hull object and set its SolidType to Accurate. Accurate enables the OffsetDistance slider. Pull it down a bit and hit
>   update. You want to get a result intersecting but showing the voronoi
>   object. If needed adjust the offset. Finally accept.
> * Now activate both the voronoi and the MakeSolid result and run BooleanUnion
> * Show the FitPrimitive object again (MakeSolid did hide it before) and run MakeSolid again in Accurate mode. Now set a slightly bigger
>   offset as you did before. The difference will determine the "lining's"
>   thickness. Accept
> * Activate the BoolleanUnion result first and the last MakeSolid result and run BooleanDifference to get a hollow object. You might use
>   another intersecting object to bool-off an opening the bottom.
>
> Harder but doable with a different workflow on an voronoi object
> owning concave regions...

## edit

Having run some trials, I can confirm this works for simple convex objects. If there are concavities, most likely the source shape needs to be chopped into sections each of which can be treated as convex.  
I played around with Meshmixer's "apply pattern" functions with limited success. I could get a form-fitting pattern shape but with a rather uneven surface. Some fine-tuning of the pattern parameters may help. Note that the new shape tends to be as thick as the original voronoi object, so it may well be better to do something like the following:  
1) create a duplicate of the original  
2) shrink the duplicate by a few percent  
3) align the two objects to a common origin and take the boolean difference to create a thin-wall version of the original.  
4) Build the pattern object based on that thinwall object.

### edit number 2

I succeeded! For those who care, I took an open Voronoi glasses case and put a skin inside to protect your glasses. See [this Thingiverse item](https://www.thingiverse.com/thing:3013220)

> **Comments:**
> **username_4**: The thing you linked shows up empty, no preview :(  
> **username_0**: @username_4  Yeah, I don't know what Thingiverse did wrong. I've tried to edit but the STL images don't show.  I'll add an actual photo one of these days.  
> **username_0**: @Trish  Amazingly enough, I found the forum page - now linked in my answer.  

---

