Matt Nelsen

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How to Construct a Tetrahedron in Blender

Feb 2007
07

This tutorial requires basic knowledge of Blender.

Background

Blender’s three-dimensional rectilinear grid allows for easy creation of cube-based objects. But what do you do if you want to create a tetrahedron, a regular polyhedron with four equilateral triangle faces? My initial attempts at this involved trying to create one face on the X-Y plane and rotating a copy up. This turned out to be a lot more trouble than it’s worth because you have to deal with some very specific angles.

After playing with a magnetic toy in the shape of a tetrahedron I realized that it could be inscribed neatly in a cube, with each of its vertexes in a corner of the cube, and each of its edges running along the diagonal of one of the cube’s faces.

In short the coordinates for the vertices of a tetrahedron are:

(+1, +1, +1)
(−1, −1, +1)
(−1, +1, −1)
(+1, −1, −1)

Constructing the Tetrahedron

Create a cube, switch to vertex select mode and rotate the scene so that you can see and select any of its vertices. The image below already has a tetrahedron inscribed in it which should help you locate the new faces you will add. Each vertex of the cube is labeled “A” to “H”:

Cube with vertices labeled
Select A, D, G. Press [F] to create a face.
Select A, D, F. Press [F] to create a face.
Select D, F, G. Press [F] to create a face.
Select A, F, G. Press [F] to create a face.

You now have a tetrahedron inscribed inside the original cube. Let’s cut away the cube:

Select B, C, H & E. Delete these vertices.

You are now left with a tetrahedron:

The finished tetrahedron


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