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

{
  "type": "crafting_shaped",
  "pattern": [
    "#",
    "#"
  ],
  "key": {
    "#": {
      "item": "minecraft:purpur_slab"
    }
  },
  "result": {
    "item": "minecraft:purpur_pillar"
  }
}