The real question is how did you knew before hand what shape will come out if you use circular pattern twice and that you should use sculp first? Because it is very difficult to immagine that before hand?
It's not the first thing I thought of. In the beginning it took me a while to figure out how to create a tetrahedron at all (using extrusion) and I played around to find cleaner/quicker ways, trying to have as few steps in the browser as possible, and in the end managed to reduce it to just a single extrusion (as can be seen in one of my other videos). Later I realised you could also cut it out of a cube because using 4 of the cube's vertices can produce a tetrahedron. Actually I first had a video using 4 individual cuts, creating an individual plane for each, but later optimised that through circular patterns so there's much fewer steps. I deleted the old video and uploaded this one then. It's the result of a process of refinement really.