Introduction: Portal Cube

If you are, like me, a fan of the Portal game series, you can easily understand the appeal of owning a physical representation of such an iconic game item: A Portal Cube.

The name of this one is the Weighted Storage Cube.
It is quite similar to the companion cube which can be made with the same instructions and very little adjustments.


The dimensions of the final product are: 9.3 cm x 9.3 cm x 9.3 cm ( 9.3 cm is about 3 2/3 inches)


  • a 3D printer ( or you can use a 3D printing service )
  • PLA 3D printing filament of various colors ( White, Black, Cyan, Silver)
  • modeling glue or super glue
  • (optional) fine sanding paper ( about 220 grit )

With this out of the way, let's get started !

Step 1: Downloading the 3D Parts

When I started this project, I looked for an existing good quality 3D model of the cube that I could adapt to my need. Most of them were too approximate or were difficult to split in combinable parts.

I decided to make my own using Blender.

I went through various iterations to adjust the model to all the constraints of the project:

  • Parts must be printable without any support
  • Model is made of various materials
  • Assembling of the model should be easy
  • Final product must feel solid and robust

I've exported all the necessary parts in STL format.

Step 2: Printing the 3D Parts

(If you don't have a 3D printer, you can use a 3D printing service and send the STL file to print)

I personally use a Prusa i3 Mk3 printer. As each printer is different, the resulting printed model quality and print time may differ from what I'll show below.

As stated in the previous step, I designed the parts so there's no need for supports.

Print parameters

I printed all the parts in 0.15mm layers, with a 0.4mm nozzle and 1.75mm PLA filaments.

I found that printing with 0.15mm layer height is good compromise between speed and quality.
Also none of the parts have enough small vertical details to justify using a lower layer height.


To print the parts you'll need PLA filament of 4 different colors:

  • White ( for the corners and the logos )
  • Black ( for the rings and face supports )
  • Cyan/Light Blue ( for the inner faces )
  • Silver ( for the outer face and logos )

The core can be printed in any colors as it won't be seen from outside.

The models shown has been printed using AMZ3D 1.75mm filament

Note: If you don't have the right colors, you can still paint the part afterwards ( see Step 3 )

Step 3: (Optional) Preparing the Parts

This part is optional as it depends on how the parts came out of the printer and/or if you didn't have the right filament colors.


If the parts are showing too much the printing layers or other printing related artefacts, you need to sand them off.

Warning : Be aware that sanding colored PLA may "whiten" the color and may require a painting step.

I usually only sand the white corners. They are the parts showing the most obvious printing artefacts. As they represent a large portion of the final model volume, those artefacts will be more obvious.

Note: I also recommend wet sanding as this minimize the airborne particles resulting from sanding the pieces.

I won't go to much in details, the Internet is full of great tutorials on post processing 3D printed parts ( see recommended link in the painting section just below )


If you need to paint the parts to get the right color, you can use a variety of techniques ( spray paint, airbrush ... )

There's a great article about post-processing 3D printed parts:

Step 4: Core and 5 Inner Faces

There's multiple ways to build the cube.

Here, I'll show the one where faces are built from the core.

This step is quite simple,

  • take the core and add glue in one of the inverse pyramidal side of it.
  • take a blue inner face and glue its tip matching a side of the core
  • Repeat the operation for the other four inner faces.

Important: Make sure to leave one of the face away for now. This will ease the mounting of the outer and support faces.

Step 5: Adding the Outer Faces

In this step, we will build the outer faces.

  • First glue each outer face and a support face as shown on the photos.
  • When glue has cured, glue each outer/support face to the 5 already attached inner blue faces.
    Warning: make sure to mount them with the correct orientation so that each black edge doesn't collide with an other.

For the last face, instructions are a bit different:

  • Take the 6th inner blue face and mount it on the last outer/support face.
  • Once done, you can finally glue this last face to the core.

Step 6: Adding the Corners

This step is quite straightforward.

  • Glue first the 8 corners
  • Then glue the edge corners ( make sure to get them well centered )

Step 7: Rings and Logos

The last steps of the build !

  • glue each ring to each face of the cube
    Warning: this is a messy step as the rings are quite small and often it's easy to add too much glue that will stain the face.
  • Mount each logo by assembling the silver back and the white aperture logo together.
  • Once done, glue a logo to each of the face of the cube.

And voila !, you are now the owner of a Portal Cube !