I learned a simple way to make a tetrahedron from Ann Tyng* by inscribing it in a cube.
See this post I did back in 2017:
A cube has six equal faces and a tetrahedron 6 equal edges, one for each face of a cube.
*Ann Tyng, was a classmate of my mother’s at Harvard Graduate School of Design, where they were among the first year of women to attend. Later she was a teacher of mine at U Penn. When you see things in Lou Kahn’s work like the tetrahedral ceiling of the Yale Art Gallery, I believe you’re seeing the influence of her on his work.