NanomaterialsNanomaterials have garnered significant interest in enhancing the performance of energy harvesting systems, biomedical devices, and high-strength composites. Despite advances in fabricating elaborate and heterogeneous nanostructuresNanostructures, and characterizing them using TEM tomography, challenges still remain in achieving straightforward 3D visualization, due to complex fabrication processes, agglomeration issues, and non-uniform outputs. Here, we propose an in situIn situ synthesis approach for fabricating complex, hierarchically assembled ZnS nanostructuresNanostructures which comprise nanowire cores and nanoparticles catalyzed by Ag2S. We have demonstrated that vaporized Zn and S solidify into nanostructuresNanostructures of various shapes under controlled temperaturesTemperature. This study marks the first successful synthesis of a heterogeneous nanostructureNanostructures, utilizing the phase transformationPhase transformation mechanisms of vapor–liquid–solid for nanowires and vapor–solid for nanoparticles through precise temperatureTemperature control. The resulting hierarchically assembled ZnS nanostructuresNanostructures were characterized, and their growth mechanisms were elucidated using the advanced TEM techniques. The electron tomographyElectron tomography and 3D printing3D printing techniques allowed visualization of these centimeter-sized nanostructuresNanostructures which has rarely been explored for randomly fabricated nanomaterialsNanomaterials. This collaborative work is expected to open avenues for fabricating advanced and sophisticated nanostructuresNanostructures with potential applications in diverse fields.