A creator can add new magical abilities to a magic item with no restrictions. The cost to do this is the same as if the item was not magical. 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 sword.
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.
Each location on the body, or body slot, has one or more affinities: a word or phrase that describes the general function or nature of magic items designed for that body slot. Body slot affinities are deliberately broad, abstract categorizations, because a hard-and-fast rule can't cover the great variety among wondrous items.
You can use the affinities in the list below to guide your decisions on which magic items should be allowed in which body slots. And when you design your own magic items, the affinities give you some guidance for what form a particular item should take.
Some body slots have different affinities for different specific items.
Body Slot Affinity
Headband, helmet Mental improvement, ranged attacks
Hat Interaction
Phylactery Morale, alignment
Eye lenses, goggles Vision
Cloak, cape, mantle Transformation, protection
Amulet, brooch, medallion, necklace, periapt, scarab Protection, discernment
Robe Multiple effects
Shirt Physical improvement
Vest, vestment Class ability improvement
Bracers Combat
Bracelets Allies
Gloves Quickness
Gauntlets Destructive power
Belt Physical improvement
Boots Movement
Wondrous items that don't match the affinity for a particular body slot should cost 50% more than wondrous items that match the affinity.