Marcel Tünnissen

Freelance artist
Hörby, Sweden

Lately I started building models of polychora. By using transparent material I

try to show all faces. This is different from what I have seen before and it

comes with some new challenges.

First of all the inside of a model, with all the imperfections, can be seen. The

tabs to glue the faces together can now be seen and they need to be as small as

possible, as a result however the relative errors become bigger. Several layers

of cells will lead to the fact that outer layers won't fit anymore. This

requires much more craftmanship than building polyhedra.

Using transparent colours influences how faces in lower layers are experienced.

If you use layers of analogous colours, it is hard to distinguish them, if you

use layers of complementary colours, lower layers will loose their effect. One

has to balance the colours carefully. Sometimes one has to break a

mathematically correct colouring scheme to get a far more aesthetic result.

Projection of a Rectified 24-cell
118 mm x 118 mm x 118 mm
Chromolux paper and coloured transparent overhead sheets

This is a model of the (4 dimensional) uniform polychoron called rectified

24-cell. It consists of 24 cubes and 24 cuboctahedra. All cubes are transparent and

8 are light pink, 8 light yellow and 8 colourless. Bright white light is needed

to be able to distinguish these colours. The cubes on the inside are a bit


The colours pink, blue and green are evenly divided over the triangles. The

colouring scheme of both the cubes and the triangles is such that a rotation

around a symmetry axis transforms one set of colours into another. For the

triangles this symmetry is partly broken by using transparent material for the

triangles on the outside, while all the others are opaque. This makes the model

visibly more attractive.