{
  "version": "0.1",
  "nodes": {
    "1": {"id": 1, "name": "outer", "op": {"type": "Cylinder", "radius": 15.0, "height": 40.0, "segments": 64}},
    "2": {"id": 2, "name": "bore", "op": {"type": "Cylinder", "radius": 10.0, "height": 40.0, "segments": 64}},
    "3": {"id": 3, "name": "pipe", "op": {"type": "Difference", "left": 1, "right": 2}}
  },
  "materials": {},
  "part_materials": {},
  "roots": [{"root": 3, "material": "default"}]
}