The scalable fabrication of 3D macroscopic solids with controllable densities of nano scale junctions between carbon nanotubes (CNTs) is reported using chemical vapor deposition. The nanoscale intermolecular junctions result in porous solids with high thermal stability, electrical conductivity, excellent mechanical properties, and structural stability in concentrated acids, bases, and organic solvents. Such CNT solids represent the next generation of carbon-based materials with potential for a broad range of applications.