So, there's something I'm not sure of. When you have a magic item, say for example a Belt of +2 Str., and you wanted to add Con +2, could you just add it onto the same item or would you have to create/purchase a whole new item? I assume the same applies to custom magic items, like a "Ring of Sustenance and Protection +2" and you wanted to make the protection a +3 or just added something else entirely to it like water walking or invisibility or something. Can you just keep adding, or would you have to create whole new items each time?
So, there's something I'm not sure of. When you have a magic item, say for example a Belt of +2 Str., and you wanted to add Con +2, could you just add it onto the same item or would you have to create/purchase a whole new item? I assume the same applies to custom magic items, like a "Ring of Sustenance and Protection +2" and you wanted to make the protection a +3 or just added something else entirely to it like water walking or invisibility or something. Can you just keep adding, or would you have to create whole new items each time?
You can keep adding. Just each additional enhancement costs 50% more. So if you've got a +2 belt of strength (4,000 gp) and want to add a +2 Con (also 4,000 gp), the price of the added ability is 6,000 gp (instead of 4,000 gp).
That's only in the case for items that take up body slots, however. Items that do not (such as weapons, ioun stones, etc) just add the costs together (though ioun stones double the cost of effects anyway).
Adding New Abilities
Sometimes, lack of funds or time make it impossible for a magic item crafter to create the desired item from scratch. Fortunately, it is possible to enhance or build upon an existing magic item. Only time, gold, and the various prerequisites required of the new ability to be added to the magic item restrict the type of additional powers one can place.
The cost to add additional abilities to an item is the same as if the item was not magical, less the value of the original item. Thus, a +1 longsword can be made into a +2 vorpal longsword, with the cost to create it being equal to that of a +2 vorpal sword minus the cost of a +1 longsword.
If the item is one that occupies a specific place on a character's body, the cost of adding any additional ability to that item increases by 50%. For example, if a character adds the power to confer invisibility to her ring of protection +2, the cost of adding this ability is the same as for creating a ring of invisibility multiplied by 1.5.
thanks