minecraft-assets/data/minecraft/recipes/item_frame.json

{
  "type": "minecraft:crafting_shaped",
  "category": "misc",
  "key": {
    "#": {
      "item": "minecraft:stick"
    },
    "X": {
      "item": "minecraft:leather"
    }
  },
  "pattern": [
    "###",
    "#X#",
    "###"
  ],
  "result": {
    "item": "minecraft:item_frame"
  }
}