Alain, you can make your model of the unaan pattern be a tetrahedron by making the three bars that connect to the white corner be the same length as the other three bars. That will force the white corner to stand out from the plane of the colored bars at the correct distance.

Also,an oblique drawing or photograph of the actual tetrahedron in the printed material would make it easier for students to visualize.

Thanks for making the DVDs available.