[@Jerkchicken]
Sorry for the delay. Counsel has deliberated and found that "molten liquid" metal felt like a conjoinment of fire and earth and thus cannot be allowed. 
We also are unsure if you would even need metal to perform projectile attacks, as the same can be done with stone.
I don't remember if we said yes to metal and earth being the same element.. Let me ask.. 
Okay, we decided you can use metal, so long as it is not molten or superheated.
*pounds gavel*