The so-called Body Forging Pod was a device Shin had developed based on his own body-forging method of using Chakra vibrations.
It had initially been created solely to forge Brutal Justice's Flesh Armor. Later, when it was used on people, its performance had been greatly reduced. After all, there was a limit to what the human body could endure, whereas Flesh Armor was merely clumps of living cells.
Since the Body Forging Pod made for humans had already reached the limit of its effectiveness on Naruto Tsunade, perhaps she could try the forging machinery used for Flesh Armor.
Naruto Tsunade, however, was suspicious of Shin's apparent kindness.
Shin took Naruto Tsunade to the Biological Science Research Institute, where she witnessed the entire process of forging Flesh Armor.
"The intensity of this machinery is several times that of an ordinary Body Forging Pod at maximum power. Can you withstand it?" Shin asked Naruto Tsunade.
Naruto Tsunade remained calm. "Those chunks of flesh won't cry out in pain. Do you think I can't endure it?"
"If you can endure it, all the better. I'm also quite curious to see where the limits of this body of yours lie."
Naruto Tsunade suddenly seemed thoughtful. "Have you always trained this way yourself?"
Shin merely said, "I did before, but I no longer need it now."
His strength had also reached a bottleneck. If he wanted to grow stronger, he could only follow the Otsutsuki's example—constantly planting Divine Trees and consuming Divine Tree Fruits to continuously enhance his Chakra.
Or he could find a new path through technology.
After ordering Tonokawa and the others to build a Body Forging Pod with the same output as the machinery used for Flesh Armor, Shin sent Naruto Tsunade home to wait for word from the Mechanical Science Research