Place an empty or partially filled saw mold into the slot to fill it with metal from the vessel. It takes 100 units of metal to completely fill an empty Ceramic Mold. The text in the vessel's GUI will be updated to show the amount of metal remaining in the vessel.
Copper
100 Units
Unshaped Ingot
To fill the saw mold from a ceramic ingot mold, right click the liquid unshaped ingot to open the casting interface:
Put the ceramic Saw mold in the second input slot and wait for the filled mold to finished.
Saw Blades can also be crafted by using ingots on an anvil with a hammer. This is the only option for higher tier metals that cannot be cast. The durability depends both on the metal used and the skill of the smith forging the tool.