Visualizing Blend Types

Tests using traditional line, triaxial, and biaxial blends can teach us a lot about ceramic chemistry.  But sometimes they feel limiting.  What other possibilities are there?  Arranging a series of line blends into a "complete graph" might be illuminating.  And instead of a flat biaxial, what about a three-dimensional pyramid/tetrahedron?  What if blends went 3d?

I'd love to hear the #glazenerd army's thoughts on other types of blends we could use.