/durability
This is a simple command to allow you to simply swap out the custom model data on an item.
/durability <block/entity> <pos|target> <slot> [add|set|remove] <value>
Syntax:
Block / Entity
This works on all types of entities, as well as storage blocks
Block: A storage-type block, such as a Chest, Barrel, or Lectern.
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Entity: A target selector, this works on all entities
Pos / Target
This is the specific coord or target of which block/entity you want to edit the info of
Pos: ~ ~ ~ coords that mark a storage block
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Entity: Target selector for which entities item you want to edit
Slot
This is the slot of the item you want to edit
Add / Set / Remove
This lets you modify the items current durability
Add/Remove or Set the durability of the selected item to whatever you desire
/durability block -1350 63 751 container.19 add 50
/durability entity @s weapon.mainhand set 20
/durability entity @a weapon.mainhand remove 15