Why did kouan yu find it very difficult to make the said bell?

Kouan Yu found it very difficult to make the bell because he faced numerous challenges, including the technical complexities involved in casting metal, achieving the right tonal quality, and ensuring the bell's structural integrity. Additionally, the pressure to meet high artistic standards and the expectations of the community added to his difficulties. Despite his dedication and skill, the intricate process required significant time, effort, and precision, making it a daunting task.