src/main/resources/assets/mekanismtools/recipes/steelleggings.json

{
  "result": {
    "item": "mekanismtools:steelleggings"
  },
  "pattern": [
    "I*I",
    "* *",
    "* *"
  ],
  "type": "forge:ore_shaped",
  "key": {
    "I": {
      "item": "minecraft:iron_ingot"
    },
    "*": {
      "ore": "ingotSteel",
      "type": "forge:ore_dict"
    }
  }
}