The process of making a Spatial Storage tool for Xiao Yin was a lot easier for Lin Mu after he had already made one for Ashy. It only took him a little over a day to finish it.
Not only did he have a lot more freedom in it as he wasn't using a restrictive material like the Lustrous Edge Obsidian, but having improved from the previous experience his speed of making it was several times faster too.
Similar to Xiao Yang, Lin Mu made a Spatial Storage Gem for Xiao Yin.
He used a Immortal Red Cuprite for it, which he shaped into a oval gem. Getting this wasn't hard as it was a mineral that was found among many others in the Dao Wind Empire and was actually a common one often used for Spatial Storage Tools.
Raw Immortal Red Cuprite was usually in the form of irregular chunks founds among other ores and was known for retaining formations well.