Priorities (3).

Working around the properties of a material was something Cain had learned to do almost instinctively as he continued to create items and weapons.

There was not just the physical aspect to consider, but also the magical as well.

What type of runes would resonate best with the materials he uses? What type of elemental affinity would he affix to the runes, which would also have to resonate with the materials?

The general shape of the item or weapon made. In more complicated cases like making a firearm, how the different parts would interact with one another, both physically and magically, and how the runes and magic circles inscribed onto these parts would resonate to produce the desired effect as a whole...

His face settling into a serene, yet serious expression, he began hammering faster, working delicately, yet quickly.