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.