The Runcitruncated 5cell
The runcitruncated 5cell is a uniform polychoron bounded by 5 truncated tetrahedra, 10 hexagonal prisms, 10 triangular prisms, and 5 cuboctahedra. It may be constructed by radially expanding the truncated tetrahedral cells of the truncated 5cell outwards and filling in the gaps with cuboctahedra, hexagonal prisms, and triangular prisms.
Structure
We shall explore the structure of the runcitruncated 5cell by means of its parallel projection into 3D.
The Northern Hemisphere
This image shows the nearest truncated tetrahedral cell to the 4D viewpoint. For clarity, we omit edges and vertices from all the other cells, and render the other cells in the light transparent color.
The hexagonal faces of this nearest truncated tetrahedron are joined to 4 hexagonal prisms, as shown below:
Straddling these hexagonal prisms are 6 triangular prisms, which share an edge with the nearest truncated tetrahedron:
The triangular faces of the nearest tetrahedron are joined to 4 cuboctahedra:
These cuboctahedra appear slightly flattened, because they are being viewed from an angle. They are perfectly uniform cuboctahedra in 4D.
The next image shows all of these cells together:
These cells are the “northern hemisphere” cells of the runcitruncated 5cell.
The Southern Hemisphere
The farthest cell from the 4D viewpoint lies on the opposite “pole” of the runcitruncated 5cell. It is a cuboctahedron:
The 6 square faces of this cuboctahedron are joined to 6 hexagonal prisms:
These hexagonal prisms look slightly flattened because they are being viewed from an angle. They are perfectly uniform in 4D. The following image shows all of them together:
Four of the cuboctahedron's triangular faces are joined to triangular prisms, as show below:
The other four of the cuboctahedron's triangular faces are joined to 4 truncated tetrahedra:
The next image shows all of these cells together:
Summary
In summary, the northern hemisphere of the runcitruncated 5cell has 1 truncated tetrahedron, 4 hexagonal prisms, 6 triangular prisms, and 4 cuboctahedra. The southern hemisphere has 4 truncated tetrahedra, 6 hexagonal prisms, 4 triangular prisms, and 1 cuboctahedron. This makes a total of 5 truncated tetrahedra, 10 hexagonal prisms, 10 triangular prisms, and 10 cuboctahedra.
The 5 truncated tetrahedra correspond with the 5 cells of the 5cell, from which the runcitruncated 5cell is derived; and the hexagonal prisms correspond with the 10 faces of the 5cell. The 5 cuboctahedra correspond with the 5 vertices of the 5cell, or, equivalently, the 5 cells of the dual 5cell; and the 10 triangular prisms correspond with the 10 edges of the 5cell (equivalently, the 10 faces of the dual 5cell).
Coordinates
The Cartesian coordinates of the runcitruncated 5cell, centered on the origin and having edge length 2, are:


Simpler coordinates can be obtained in 5D as all permutations of coordinates of:
 (0, √2, 2√2, 2√2, 3√2)
The 4D coordinates are derived by projecting these 5D coordinates back into 4D using a symmetric projection.