Quantum-dot superlattices provide a new horizon in fundamental physics. The fabrication and characterization of well-defined 3D superlattices made of silver nanocrystals is described in this communication. "Supra crystals" of relatively large sizes could be obtained with very high reproducibility. The picture shows an SEM image at a 45 degrees tilt of the silver nanocrystal aggregates on an HOPG substrate.