ItemMaker - TheDevTec/TheAPI Wiki

All options:

path:
  # Availible types: MATERIAL (or ID), BANNER, LEATHER_.., PLAYER_HEAD, POTION, ENCHANTED_BOOK, WRITTEN_BOOK (WRITABLE_BOOK) 
  type: ""
  displayName: ""
  lore:
  - "..."
  amount: 1 # Default amount is 1, you do not need to add this if you want just 1 item :)

  nbt: "" # Usualy nbt is loaded first and then other options. So for example item name will be used (rewritten) from 'displayName' section.
  damage: 5 # Or durability
  unbreakable: true/false
  
  # You can find ItemFlags at: https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/inventory/ItemFlag.html
  itemFlags:
  - "FLAG"
  
  # ModelData is used to apply custom textures
  modelData: 1

  # If type is BANNER, you can specify more options here...
  banner:
    # You can find availible patterns at: https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/block/banner/PatternType.html
    # Pleasu use this format: "COLOR:PATTERN"
    patterns:
    - "RED:STRIPE_TOP" // "COLOR:PATTERN"

  # If type is LEATHER_... (leather armor), you can specify more options here...
  leather:
    color: "RGB"

  # If type is PLAYER_HEAD, you can specify more options here...
  head:
    # You can use this types: PLAYER, VALUES, URL
    type: ""
    owner: ""
  
  # If type is POTION, you can specify more options here...
  potion:
    # Availible potion types: https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/potion/PotionType.html
    # You can find effects here: https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/potion/PotionEffectType.html
    type: ""
    # Please use format: "EFFECT:duration:amplifier:ambient:particles"
    effects:
    - "BAD_OMEN:50:2:true:true"

  #You can find availible encahnts at: https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/enchantments/Enchantment.html
  #Please use format: "ENCHANT:level"
  #If type is ENENCHANTED_BOOK, then the book will have these encahnts
  enchants:
  - "KNOCKBACK:5"
  
  # If type is WRITTEN_BOOK, you can specify more options here...
  book:
    author: ""
    # Availible generations: https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/inventory/meta/BookMeta.Generation.html
    generation: ""
    title: ""
    pages:
    - "page1 ....."
    - "page 2 ...."

Examples:

This example is from ServerControlReloaded GUI kit example...

items:
  add:
    stone:
      type: "STONE"
      amount: 12
      displayName: "&uMagic stone"
      lore:
      - "&7This stone is so magical, it can push enemies"
      enchants:
      - "KNOCKBACK:5"

Head example

path:
  type: "PLAYER_HEAD"
  displayName: "Custom head"
  head:
    # You can use this types: PLAYER, VALUES, URL
    type: "VALUES"
    owner: "eyJ0ZXh0dXJlcyI6eyJTS0lOIjp7InVybCI6Imh0dHA6Ly90ZXh0dXJlcy5taW5lY3JhZnQubmV0L3RleHR1cmUvMjcwNWZkOTRhMGM0MzE5MjdmYjRlNjM5YjBmY2ZiNDk3MTdlNDEyMjg1YTAyYjQzOWUwMTEyZGEyMmIyZTJlYyJ9fX0="