In the clean room, roughly shaped plutonium hemispheres came in at one end, were machined into their final shapes at several stages, and emerged from the other end so polished they looked like glass. Each was then placed in a plastic holder and hand-carried out of the machine shop to the storage room, where each was set on an individual shelf made of steel covered with plastic. Metal contact could not be allowed, because plutonium, in addition to being radioactive, and warm due to its alpha-radiation decay, was a reactive metal, quick to spark on contact with another metal, and actually flammable. Like magnesium and titanium, the metal would burn with gusto, and, once ignited, was the very devil to extinguish. For all that, handling the hemispheres—there were twenty of them—became just one more routine for the engineers. That task had long since been completed.

The harder part was the RV bodies. These were large, hollow, inverted cones, 120 centimeters in height and 50 across at the base, made of uranium-238, a darkly reddish and very hard metal. At just over four hundred kilograms each, the bulky cones had to be precisely machined for absolute dynamic symmetry. Intended to "fly" after a fashion, both through vacuum and, briefly, through air, they had to be perfectly balanced, lest they become unstable in flight. Ensuring that had to everyone's surprise turned out to be the most difficult production task of all. The casting process had been reordered twice, and even now the RV bodies were periodically rotated, similar to the procedure for balancing an automobile tire, but with far more stringent tolerances. The exterior of each of the ten was not as finely machined as the parts that went inside, though they were smooth to the ungloved touch. Inside was something else. Slight but symmetrical irregularities would allow the "physics package"—an American term—to fit in snugly, and, if the moment came—which everyone hoped it would not, of course—the enormous flux of high-energy "fast" neutrons would attack the RV bodies, causing a "fast-fission" reaction, and doubling the energy released by the plutonium, tritium, and lithium deuteride within.