A6 and O6 are, loosely put, stretched and squashed cubes.
All are made from `diamonds'.  A diamond is a planar quadrilateral with
all four edges about 32mm, short diagonal 34mm, long diagonal 54mm.
(Maybe the triangles are ideally equilateral? - No, or the obtuse solid
would be planar.)  Obtuse solid with one plane horizontal, opposite
plane is 17mm up.

Assemble three acute corners to get a pointy three-diamond; two of
those go together.  Similarly, assemble three obtuse corners to get a
nearly-flat three-diamond; two of those also go together.

ACUTE		A6
OBTUSE		O6
BILINSKI	B12 = 2 A6 + 2 O6
FEDEROV		F20 = 1 B12 + 3 A6 + 3 O6
KEPLER		K30 = 1 F20 + 1 B12 + 5 A6 + 5 O6