Tetrahedron, Octahedron.

Creating tetrahedron and octahedron with tools: 3D rotate,3D array and  3D mirror.
For creating tetrahedron we built equilateral triangles and aligned to the vertical axis located in the centre of the central triangle.

Then we used 3Darray -polar  and finished the tetrahedron.

For creating the pyramid with the square on the base we used the same technique.

Tool: Align

Tool: 3Darray (polar)

For creating octahedron we can use 3Dmirror on the made pyramid and use the square base as a mirror.

  

Link for the DWG file: https://drive.google.com/open?id=10IjQiWhCU4unE3xVvEmTGR0L9yAXOSou