Three squares are joined around a triangle; then the squares are rotated around the edges of the triangle until the vertices meet to form an octahedron frame. A solid octahedron can be moved into the frame. You can control the size of the balls at the vertices and the diameter of the cylinders that make up the squares. Use the switch to show the faces of the squares. This idea can be used to build a physical model out of flexible bars such as straws.