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