Abstract: Carbon nanotube foams are provided which comprise tubes substantially aligned longitudinally in a first direction, wherein: each tube defines an outer wall and an inner wall, and each tube comprises an entangled bundle of carbon nanotubes substantially aligned longitudinally in the first direction; and tubes in at least a subset of the tubes are positioned with respect to each other to form one or more first hexagonal units, wherein each first hexagonal unit comprises first-hexagonal-unit tubes, wherein the first-hexagonal-unit tubes comprise six peripheral first-hexagonal-unit tubes and a central first-hexagonal-unit tube, wherein the six peripheral first-hexagonal-unit tubes surround the central first-hexagonal-unit tube in a juxtaposed, hexagonal configuration. Articles of manufacture, e.g., helmets, comprising the foams are also provided which are configured to cover at least a portion of an object, e.g.