Is there the equivalent of a Necklace of Fireballs for other types of Energy, such as Cold, Acid, etc.? If so, how much would such a thing cost/weigh? What slot would it take up, if any?
There isn't one in the rules, but I don't think it's a stretch to say that if you were to homebrew such an item, just have it basically the same as the existing one, just change the energy type.