BearF.
Understand what you're saying,but I'm having difficulty with this 2d/3d thing.
As I see it, the least number of finite elements needed to construct a 3d shape would be 6 - in the form of a 'triangular' pyramid.
From there, an Infinite number of elements can describe anything. So put enough 2d shapes together and you get a bumpy 3d. The more you add the smoother the surface.
The thing I'm stuck on is where you say that a tube is better in tension than compression. Hilberts' Regression suggests otherwise, or have I got that wrong?