Being a bit of a wordsmith, I have long been unsure what the correct spelling is for the tool we use to cast round balls. Is it ''mould" or "mold"? To my way of thinking, "mold" is the fungus stuff that grows in moist area and "mould" is the casting tool. So, I looked it up. Surprise! Do yer own thang. Both are correct and interchangeable for the casting tool. "Mold" is a more American usage and "mould" is more British but either is acceptable. Potato/potaato?