This simple shape can be used create numerous complex and interesting 3D tilings and formations.
The parallelepiped is essentially an octahedron with two tetrahedrons attached to opposite faces, so the tiling is based on the octahedron and tetrahedron pattern found in an octet truss.
The holes are sized for 1/8" cylindrical neodymium magnets, 1/32" long. This size of magnet was selected for cost reasons and to minimize the repulsive forces between the magnets at each tip. This size of magnet is not very strong on its own but suffices when there are multiple faces joined together. If you choose to scale the model larger, you will want to use larger magnets.
The six magnets at the two tips are all inserted with the same polarity, the remaining six magnets around the center are inserted with opposite polarity. It is a good idea to clean the holes out first with a 1/8" drill bit. CA glues works well. See here for a video on how to assemble the first and second level cuboctohedron: https://youtu.be/Fpc0BToJeA0
The first level cuboctohedron is made with 12 individual parallelepiped shapes, the second level cuboctohedron is made with 36 individual parallelepiped shapes