This is the most complex of the six regular 4-dimensional solids, the 600-cell. It's sometimes thought of as the analogue of the icosahedron, and has (as you might expect) 600 tetrahedral cells. This wasn't easy to model in 3-space, and for it I used an orthogonal projection rather than the Schlegel diagrams of the other polytopes I build. This allows it to be a reasonable size (rather than twice as large and costing 8 times as much) and also to be structurally sound – that's always good in a sculpture.
In this projection all cells are identical, as there is no perspective distortion. It seems complicated from many angles, but as it rotates, every so often things line up beautifully along the overall cubic symmetry.