Solid Surface Hollow Sphere
The entire sphere is built with a contiguous Face Centered Cubic lattice. The surface is 4 or 5 balls thick for strength and stiffness (with more at the bottom to support the weight). The Face Centered Cubic structure results in features that correlate with features of a cuboctrahedron.
25 cm (50 magnets) in diameter - just under 10 inches. About 32,700 magnets used; weight 34 lbs. (15.4 Kg)
Inspired by Boyd Edwards' Solid Sphere.
See this tutorial
for how to build a smaller version.