This is a 3x2x1 unit-cell of MPM-1-Br, a porous metal-organic framework with a cool honeycomb-type topology. It is the analog of MPM-1-Cl, which was made earlier: http://pubs.acs.org/doi/abs/10.1021/ja4054948.
Each tiny sphere represents an atom. There are 7,174 atoms in the model. The longest axis (x, or a, in this case) is ~90 Angstroms long.
That's roughly 10^-8 meters long.
So about 400,000 of these nanostructures (the .stl model) could fit in a 4mm needle tip.
I managed to print this using FlashPrint software for slicing (which comes with the CreatorPro printer).
Infill 100% is best. For supports I used PVA, a water-soluble plastic. The model itself is PLA.
I successfully printed it in 48hrs on a FlashForge CreatorPro printer.
I used CH2Cl2 (dichloromethane, DCM) to smooth edges and cold-weld some fragmented pieces together