Cube with 1/6 Tetrahedron 1/4 Octahedron Pieces

Commissioned piece, made by student Jon Ehrmann, 1978. Assembles in 2 different ways, first as the tetrahedron with partial octahedron, and then as an anti-prism (a flattened octahedron) using all of the pieces together. The volume math is essentially 1+1 = 2, tetrahedron+(octahedron/4) = antiprism.https://digitalcommons.risd.edu/loeb_models/1228/thumbnail.jp