*Wiro wrote:How the heck are you supposed to make a mold out of stone? and what about steel? Are you going to use your hands to shape steel into a mold?
Clay is good, but stone mould can be formed with a chisel and grinder.
Steel, could, also be used but to make a meatal mould you need another mould made of a wood box, filled with sand... kind of pointless because you could just use the sand-box mould. However bottles aren't traditionally made with moulds, unless the mould is attached to some kind of rotary device and the melted sand poured in.
As Pisc said, it's usually made from being blown...