Are you interested to know the power of transmission electron microscopy for 3D imaging? Read the latest perspective article published in ACS Materials Au. The perspective highlights the contribution and the importance of TEM tomography in the structural understanding and engineering of self-assembled nanostructures with specific emphasis on colloidal capsids, composite cages, biohybrid superlattices with complex geometries, polymer assemblies, and self-assembled protein-based superstructures.