Iron: moves with most force, creating the strongest limbs. 
Difficulty: 3

Copper: moves the fastest, good for skilled laborers. 
Difficulty: 4

Mercury: stimulates healing, and particularly advanced enchantments can repair breaks and cracks in metal. Repairs it makes in metal merely fuse it back together. It cannot repair broken devices with moving parts. 
It is a catalyst and is not used up when it takes effect. 
Difficulty: 7(9 to repair metal). 

Titanium: can be made indestructible. A tricky thing to do, because once this enchantment is placed the piece becomes inalterable. A blade would remain sharp forever, but a box of titanium could never be opened. 
Difficulty: 6

Aluminum: can levitate. The strength of its lift depends on the skill of the Magi, and the mass of aluminum. 
Difficulty: 6

Silver: can be made significantly more malleable. Good for anything mimicking organic movement.
Difficulty: 8

Gold: can transmit nerve signals back to the owner. Different configurations can be used to simulate different sensations. Gideon and Duncan work extensively in gold. 
Difficulty: 9


Platinum: absorbs and steals magical properties. Can pierce titanium because it becomes indestructible while stripping titanium's indestructibility. 
Bonds to its owner apparently of its own accord. The bond is strong and takes a long time to transfer to a new owner. The owner can control its movement, and if there is levitating aluminum around it can fly around by its owner's will. 
Powerful, dangerous, and ironic. It's the height of Technomancy, but renders all nearby Technomancy useless and can only be used by a fully organic(or fully platinum) being.
Difficulty: impossible. There are known examples of it, but no living Magi has been able to perform the enchantment, and few Artificers can even get their hands on the metal to work with it.