Introduction: Glow in the Dark Voronoi Christmas Decoration

It's Christmas time :) and every year I'm trying to make my own decorations and ornaments related to this special time. Few years back I have designed and made few different decorations using my small laser cutter and various colour acrylic .You can find all my patterns on Thingivers:

This year I have decided to put my 3D printers to good use and make new Christmas ornaments. In this Instructables I will show you, step by step, how to design and make Voronoi style Christmas decorations. I also decided to use 'Glow in the dark' PLA which gave pretty cool results and I hope you will like it too.


- PLA (Glow in the Dark, Gold or any other colour that you prefer)

Suppliers: Formfutura, 3DFilaPrint, ColorFabb, Amazon

- String

- Glitter spray paint (optional)


- FDM 3D printer

- Stanley knife

- Scissors


- Fusion 360

- Meshmixer

- Cure (or any other slicing software)

- Microsoft Visual C++ Redistributable (optional)

Step 1: Fusion 360

Fusion 360 is available for free if you register as a hobbyist and use it only for your own purpose. Once you install Fusion 360, you can create simple shapes very easily and, if you fall in love with it, then you can experiment with more complex shapes and patterns. There are many tutorials available on Autodesk website and YouTube.

In this instructables we just want to make simple sphere and then convert it to Voronoi pattern. To do that follow steps below and screenshots above.

- Open Fusion 360

- Click 'Create' in the top menu

- Fusion will ask you to choose the plane, and in this case choose any of 3 planes

- Click on the origin point and the sphere will appear and you can then adjust the size (I recommend 70mm)

- Expand left drop down menu under 'Bodies'

- Right click (mouse) on the Body1 and press 'Save as STL'

- Give your stl file a name and save it on your computer

- We have finished with Fusion 360 and you can close the program now

NOTE: After watching few tutorials you could make more complex patterns that you can then convert to Voronoi style, but in this Instrucables we will focus more on creating Voronoi effect using Meshmixer rather than designing lesson.

Step 2: Meshmixer Part 1

Download and install Meshmixer. If for some reason you will see error 'VCRUNTIME140.dll', especially when running Windows 10, don't worry. All you have to do is to download and install the newest version of Microsoft Visual C++ Redistributable (make sure you download right version x86 or x64).

- Open Meshmixer and press '+' icon to import your STL file that you have just created in Fusion 360

- Go to 'View' and 'Enable Wireframe'. This will allow you to see of how many triangles your sphere is made of

- Go to 'Select' on left side menu and select small area of the sphere by clicking left button on your mouse

- Go to 'Select' -> 'Modify' -> 'Select All' and sphere should appear orange, which means entire object is selected

- Go to 'Select ' -> 'Edit' -> 'Reduce' -> 'Accept' and the triangles should become larger now

Step 3: Meshmixer Part 2

- Go to 'Select' -> 'Brushes' -> 'Reduce' (see first picture above)

- Left click your mouse and use brush on your sphere. Try to change size of the brush to make variable triangle sizes. This will create really nice Voronoi (pattern later (see second picture above)

- Go to 'Edit' -> 'Make Pattern'

- In 'Make Pattern' menu choose 'Dual Edges', adjust 'Element Dimes' and once you happy with the pattern click 'Accept'

Step 4: Meshmixer Part 3

Once you pressed 'Accept', Meshmixer will generate new pattern and new window will pop out where you can see two different files. One is your old solid sphere and the other is spherical Voronoi pattern you have just created.

- Select the OLD sphere file and remove it by pressing 'bin' icon at the bottom of new window

- Go to 'Edit' -> 'Make Solid'

- New menu will appear with 'Make Solid' options, press 'Accept'

- Another window will pop out with two files, sphere pattern and sphere pattern solid. Remove the sphere pattern and leave sphere pattern solid.

- Go to 'Export' and save your sphere solid pattern on your PC as STL

Step 5: Slicing

Download and install Cura software or other slicing software that you normally use to set up your STL files for 3D printing.

- In the basic setting you have to setup the support material and brim, as the sphere is very difficult to print otherwise

- By trial and error, I have figured out that the best settings are: Overhang Angle: 70, Support infill 5% and Brim 20mm

- I used 'Glow in the dark green' PLA which you can buy on Amazon or eBay, and I printed the Voronoi Sphere at 210 Celsius nozzle and 70 Celsius bed temperature

- As for the speed I recommend to slow it down a little bit to 40mm/s - 50mm/s, but that of course depends on the quality of PLA and your 3D printer

Step 6: More Shapes

Here you can find couple of shapes that you can download and setup on your 3D printer. You will also find the original solid shapes created in Fusion 360, so you can experiment with them in Meshmixer to create your own custom Voronoi patters.

You can also use different PLA colours like Glow in the dark - Blue, Gold finish or Silver finish PLA. As an addition, you can use white glitter spray paint to simulate snow effect on your ornaments.

Step 7: Finishing Touch

Once your Voronoi Christmas decoration is printed, use Stanley knife to carefully remove brim and support material. You might have to remove some plastic residues all around the sphere.

You can experiment with retraction distance and speed in your slicing software to find best setting for this type of shape. In my case, in Cura, 4.5mm retraction distance and 40mm/s retraction speed works quite well.

Lastly cut about 10cm of string and make a closed loop so you will be able to hand your decorations on Christmas tree.

Have a Happy Christmas :)

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