The properties of carbon nanotubes, discovered by Sumio Iijima of the NEC Corporation in the early 1990s, are discussed. Carbon nanotubes contain up to 50 cylinders nestled inside each other with hemispherical caps like geodesic domes situated at the ends. Iijima and others discovered that these tubes have exotic electrical properties: They can act either like metals or like semiconductors, depending on their geometry. However, discovering a method of exploiting the tubes' unique properties has proved difficult. A technique outlined in Nature in June 1995 may alter that. This technique permits nanotubes to be coated with other materials and thus, perhaps, to become the scaffolding for structures so minute that they are dwarfed by living cells.