When the object is picked-up by the Player, create a different object and add that to the inventory instead. The Engine Features\Stack Count is copied to the new item. The old object is destroyed. Link to the archetype of the new object using Transmute. In System Shock 2 use Mutate instead. The script will look search its parents for the link, so you can create many mutatable objects from a single archetype or metaproperty.