Half of a 120-cellby
Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:1145123.
This model is featured in figure 3.22 of Visualizing Mathematics with 3D Printing.
This is joint work with Saul Schleimer.
The 120-cell is one of the six regular 4-dimensional polytopes. This is the result of taking the edges of the polytope, radially projecting them onto the unit 3-sphere in 4-dimensional space, then stereographically projecting the result into our 3-dimensional space. We remove the half of the design in the hemi-3-sphere nearest to the projection point, which makes printing the image in 3-dimensional space feasible.