20 is not the end. I see more the boundary at 30 to weave polyhedra around a sphere. 30 comes from the 30 equal edges of a dodecahedron or icosahedron.
Here an example with 30 regular cubes.
I see it looks more and more like a ball of wool. :-)
Folder: Dirk Eisner
Designer of the modules: Tomoko Fuse, Francis Ow, Dirk Eisner, Michal Kosmulski, ....
paper ratio, when extra amount at each end is equal to frame width: length : width = 2.56 : 1
paper ratio, when extra amount at each end is 3/4 of frame width: length : width = 2.435 : 1
no glue !!!!!!!!