Peter Jepsen wrote:Ooh, this is really really clever Eric!
Compliments!
Thank you very much Peter

Now I'd like to find a way to twist the vertices even more (an extra notch or two), but I can't figure out how to do this yet.
If you look closely, the edge that starts from each vertex (underlined by my colored rods
here) does not go towards the opposite vertex (otherwise it would be a simple tetrahedral pyramid), but reaches the edge that starts from it, 3 rods below. What would it look like if it was 4 or 5 rods down? Probably an even more rounded shape?
There are clues
in there, but it remains to be worked on.
If you look at
this example (which I found yesterday while searching the forum), the tetrahedron is less twisted since the edge starting from one vertex reaches at one rod under the next vertex. And it's not a question of overall dimension of the construction, since my medium-sized berlingot (a little shorter) is twisted 2 rods under the next vertex.
If anyone has an idea about that, I'm a taker.