A "holy mould" can be purchase from a crafting store, the grand exchange or traded from another player.
Well, I don't think that there is a holy symbol mould. But Ice Fiends drop the Necklace. Or I think that a holy mould is what your looking for..
To make a holy symbol on RuneScape, you need a holy mould, a silver bar, and a certain crafting level.
Holy poo!
You can get a holy mould from Al-Kharid or from the Grand Exchange.
Im assumeing your talking about the quest that you need the key.To do this just buy a key mould,it tells you where to...then get some clay and use it on the mold. Thats really the only use molding clay has in runescape.
You can purchase one in the Grand Exchange.
You must do the dwarven cannon quest, so you can buy the cannonball mold. Then all you need is the mold and steel bars. Which you then smelt together.
You can make different objects, with different moulds. Basically you take the mould and one or more metal bars to a furnace. For example: to make a holy symbol, you take a silver bar (or more than one) to a furnace, together with a holy mould. Then you click on the furnace and select the object you want to make.
You take a sickle mold and bring a silver bar and use them on furnace.
You can buy soft clay on ge, and you can buy a key mold.
Either make one using a silver bar and a tiara mold or just buy one.
first you need a holy mold and you need a silver bar then you take them to any furnace use the bar on the furnace or the mold and then it should let u make 1 also depending on your crafting level