minecraft-assets/data/minecraft/recipe/iron_door.json

{
  "type": "minecraft:crafting_shaped",
  "category": "redstone",
  "key": {
    "#": "minecraft:iron_ingot"
  },
  "pattern": [
    "##",
    "##",
    "##"
  ],
  "result": {
    "count": 3,
    "id": "minecraft:iron_door"
  }
}