The answer was that he knew how from the very beginning!
An Jing had always possessed extraordinary talent in the Dao of Artifact Crafting. Creating the Martial Meridian Array Diagram had already given him a wealth of experience in arrays, or at least in array formations related to cultivation methods. Furthermore, he had been the first to review the Yuhuadao data and various practical examples shown to everyone. Coupled with his experiences in the Tianyuan realm, where he had analyzed combat data and dissected physical Yuhua battle bodies, he had long since understood the crux of the matter, which enabled him to explain the essentials to the others.
After observing the Realizers, True Monarchs, and even Heavenly Monarchs jointly forging the Zhulong battle body, An Jing gained new insights into this path. Now, supported by an Epiphany, of course he knew how!
Chapter 741