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

{
  "type": "crafting_shaped",
  "group": "carpet",
  "pattern": [
    "##"
  ],
  "key": {
    "#": {
      "item": "minecraft:light_blue_wool"
    }
  },
  "result": {
    "item": "minecraft:light_blue_carpet",
    "count": 3
  }
}