## A Zometool model of an 8 cell

Here we describe how to build a cell-first projection of the 8 cell, one of the six regular polytopes in 4-dimensional space, using the zometool system. For the model you need

• 16 balls,
• 12 long blue (b2) struts,
• 12 medium blue (b1) struts,
• 8 short yellow (y0) struts.

For further information and instructions you might also wish to consult one of the following webpages:

The pictures below were taken by Eva-Maria Gassner.

Step 1

Use the b1 struts to build a cube. This will be the central cubical cell of the projection.

Step 2

Use the y0 struts to build 8 yellow lollipops. Mount them on the vertices of the blue cube such that they are outwards pointing.

Step 3

Use the long blue struts to connect the balls at the loose ends of the yellow lollipops

The model is now complete and you can see all cells. The cubical central cell was constructed in step 1. It is the image of two cells of the 4d polytope. Note that the central cell is surrounded by six squashed cubes, which represent the projections of the other cells of the 4-dimensional polytope.