Just to make it clear as to why someone would spend the money getting a wax melting device or a double boiler, when wax starts to boil, it can catch on fire, then you suddenly have a huge pot
of fire that can not be put out with water. Repeat DO NOT use WATER to put out a WAX FIRE! Like flaming grease, wax will explode when hit with water, splattering napalm all over you and your kitchen. I've done this at a campfire before (from a far distance with special equipment designed for the purpose) and it was a rather spectacular fireball, had a person been next to it, they would be in SERIOUS trouble.
So don't mess around trying to melt wax in a single pan, not worth the risk, especially when all one needs to make a double boiler is one pot that's bigger then the other.