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This is a close packing of 4 spheres with centers at the vertices of a tetrahedron. The spheres are each formed with 4 great circle strips which are parallel to an inscribed tetrahedron, and rotated so that the strips align with the contact points of the spheres. This was designed in Mathematica and thickened in Blender. The strips are 1.5 mm square, to be printable in metals, and all plastics.