{
  "version": "0.1",
  "nodes": {
    "1": {
      "id": 1,
      "name": "OuterCylinder",
      "op": { "type": "Cylinder", "radius": 15, "height": 40, "segments": 32 }
    },
    "2": {
      "id": 2,
      "name": "InnerCylinder",
      "op": { "type": "Cylinder", "radius": 10, "height": 40, "segments": 32 }
    },
    "3": {
      "id": 3,
      "name": "Pipe",
      "op": { "type": "Difference", "left": 1, "right": 2 }
    }
  },
  "materials": {},
  "part_materials": {},
  "roots": [
    { "root": 3, "material": "default" }
  ]
}