Su Xiao's negotiations with Donquixote Doflamingo could fall apart at any moment, but judging from the current situation, the two sides had clearly reached an agreement.
Su Xiao gave Doflamingo a list. The genuine materials needed to manufacture Alchemy Bombs and Apollo naturally did not exist in the One Piece World, but Doflamingo had manufactured explosives for the World Government before and knew what materials could be used as substitutes. All of them could be found in the One Piece World.
Doflamingo immediately arranged for people to purchase the materials. He was clever, however, and made the purchases through underground channels. As the leader of the underworld, Doflamingo had an extensive network of suppliers.
At first, Doflamingo wanted to arrange for Su Xiao to manufacture the bombs at the underground port, but Su Xiao refused on the grounds that the environment was too damp. He instead set the manufacturing site on the fourth floor of the villa—the top floor.
Doflamingo naturally disagreed. Not only did Doflamingo object, but everyone in the Donquixote Family opposed it as well. Sugar put it bluntly: "I don't want someone making bombs over my head."
After some negotiation, the manufacturing site remained on the fourth floor of the villa, on the condition that Pica thicken the walls and floor of the fourth floor to three meters.
Su Xiao knew that his cooperation with Doflamingo was highly unstable. After defeating the Big Mom Pirates, the two sides were very likely to part ways, but that was unimportant.
Pica completed the wall-thickening work in only two hours. He had not merely thickened the walls—he had also compressed the layers of rock and added steel plates inside them. Now, even if a cannonball struck the fourth floor of the villa, it would not leave so much as a