Verified answer

You need a silver bar and a mould of what you want to make. Use the bar with the Furnuss and you will make 1!!

Hope it helps and i hope its best answer!

You need to have a mold. It's available in the crafting guild. (I have not played for so long, I don't remember the city it's next to...it's just south west of it....I think the city is Falador....or something like that.

You may be able to buy the mold elsewhere, or from another player. Then, just use it on a furnace with a bar of silver. If I remember correctly, you'll need to have the item blessed in order for it to be a holy symbol.

How bout you craft a barrier between you and your addiction to video games and play outside?