The materials were not the issue. While Su could understand that they were very spread out when it came to the different storehouses they were in, that was no issue. She could easily handle that.
The dwarven storage in the underground sections had been set up to protect the strongest earth elemental materials. Most of them even needed to be kept in earth mana formations so that the mana within them did not deteriorate.
The theoretical spatial mana alloy had to be made using a purified steel. Made up of three different metals that had all been purified to only contain earth mana. This was not because the heart mana itself was important but the lack of other manas within.
The purity would allow for a stronger and more intricate rune formation to be carved in to the item that would not degrade over time. From there, it could also be able to withstand the high mana flow from unique mana gems.
Creation is hard, cheer me up! VOTE for me!