This model’s structure is an octahedron whose each face was replaced with a pyramid of three equilateral right triangles, pointing inwards. Units are located on the edges of those pyramids. Due to geometric relations between the octahedron and the cube, this results in the tips of the pyramids all meeting in a single point, in the octahedron’s geometric center. This results in a weird-looking model with lots of empty space around its faces.
Compare with an icosahedron built using the same technique.