The assemble-list JSON format

--load-assemble-list <file.json> builds the entire scene from a JSON manifest instead of positional model files. The JSON is the sole geometry source: it enumerates one or more plates, and for each plate it lists the STL or OBJ files to load, how many copies of each, where to place them, which filament slot to assign, how to merge volumes into composite objects, and what per-object or per-plate configuration overrides to apply. Passing this flag and positional model files at the same time is a hard error; the two are mutually exclusive.

This page documents Bambu Studio's parser. Orca Slicer is a fork of the same engine and reads the file identically.

Top-level object

The root is a JSON object with exactly one key that the parser reads. The file must be valid JSON or the run aborts.

Plate object

Each element of plates is an object with these fields.

Object entry

Each element of a plate's objects array names one geometry file and how to instance it.

subtype values

The subtype field accepts exactly these five strings. Any other value silently becomes normal_part.

Sub-schema: height-range entry

Used in an object's height_ranges array and in an assembled_params entry's height_ranges array.

Sub-schema: assembled_params entry

Each entry applies extra configuration to a merged composite object after all of its component volumes are combined.

Semantics that trip people up

Validation and errors

Any of these aborts the CLI rather than producing partial output.

Worked examples

Auto-arranged multi-object plate

body.stl loads once on filament 1. lid.stl loads three times: copies 1 and 3 on filament 1, copy 2 on filament 2, all sharing the print_params. need_arrange: true lets the slicer place all four objects.

{
  "plates": [
    {
      "plate_name": "Top Plate",
      "need_arrange": true,
      "objects": [
        { "path": "/models/body.stl", "count": 1, "filaments": [1] },
        {
          "path": "/models/lid.stl",
          "count": 3,
          "filaments": [1, 2, 1],
          "print_params": { "layer_height": "0.1", "support_type": "normal(auto)" }
        }
      ]
    }
  ]
}

Locked layout with a merged object and layer ranges

base.stl and top_modifier.stl share assemble_index: [7], so they merge into one object called assemble_7. The plate is locked, so both volumes stay at their coordinates. After merging, assembled_params adds a support override and a 0.3 mm layer-height band for the bottom 5 mm, and plate_params disables timelapse for this plate only.

{
  "plates": [
    {
      "plate_name": "Assembly Plate",
      "need_arrange": false,
      "plate_params": { "timelapse_type": "0" },
      "objects": [
        {
          "path": "/models/base.stl",
          "count": 1, "filaments": [1],
          "subtype": "normal_part", "assemble_index": [7],
          "pos_x": [50.0], "pos_y": [60.0], "pos_z": [0.0]
        },
        {
          "path": "/models/top_modifier.stl",
          "count": 1, "filaments": [2],
          "subtype": "modifier_part", "assemble_index": [7],
          "pos_x": [50.0], "pos_y": [60.0], "pos_z": [10.0],
          "print_params": { "infill_density": "80%" }
        }
      ],
      "assembled_params": [
        {
          "assemble_index": 7,
          "print_params": { "support_type": "normal(auto)" },
          "height_ranges": [
            { "min_z": 0.0, "max_z": 5.0, "range_params": { "layer_height": "0.3" } }
          ]
        }
      ]
    }
  ]
}