With Ace gone off to sail with the crew, only Enel and the others remained by Leo's side. Leo then assigned Enel a task: making cannons.
To be honest, Enel was nearly bored out of his mind. But there was nothing he could do; he was still Leo's "prisoner," after all, so he could only obediently follow Leo's arrangements.
Because there was no equipment to test it, no one had yet been able to determine the temperature of Enel's Lightning Metallurgy. Yet he molded metal as easily as clay—metal conducted electricity but not fire. Ace merely had the Flame-Flame Fruit, not some Heat-Heat Fruit, so his processing of metal worked from the outside inward.
Electric Metallurgy, on the other hand, had an innate advantage when it came to shaping materials.
Relying on that advantage, Enel processed most of the parts himself.
Moreover, making cannons—or rather, small, light cannons—was even simpler than he had imagined.
The Mosin-Nagant required large numbers of springs, complex-shaped bolt handles, and all sorts of screws. At first, he had been honing his fine-control skills, but later on, it became nothing but mechanical repetitive labor. He had thoroughly become a tool worker.
But cannon manufacturing was actually simpler than gun manufacturing. In theory, the barrel and gun body needed to be cast separately, but this was merely an experimental light cannon, so everything was simplified. First came the barrel: 105 millimeters in caliber and three meters long. Then came the breech lock.
Normally, a breech lock needed rubber for sealing and cushioning. The battle when Luffy and the others reached Sky Island had shown that this world already possessed rubber and even used it in industry. But their materials were scarce, so the breech ultimately used a screw-type structure. It was, in truth, a Napoleon Cannon built