FreeCAD → Bambu Studio → Print MCP

Portable Python 3.11+ MCP and CLI for a reviewable FreeCAD-to-Bambu workflow. It keeps CAD execution, bounded 3MF preflight, explicit review, LAN upload, and status/control in one durable job record.

Scope

• FreeCAD scripting through the separately installed neka-nat/freecad-mcp addon, using localhost XML-RPC and pinned revision 3da6db5f71a7b74d1b69d295d1ba89233ad622b5.

• Bambu Studio GUI slicing with a human preview checkpoint, or CLI slicing only with explicit machine/process/filament profiles.

• Native single-plate dispatch for A1, A1 mini, P1P/P1S, X1C/X1E profiles. AMS mapping, fresh status, pause, resume, and stop are explicit workflow operations.

• Experimental LAN MQTT/FTPS transport. H2, cloud, FEM and proprietary client-certificate extraction are outside this release.

FreeCAD 1.1.3 CAD export and Bambu Studio 2.8.2 GUI slicing/preflight were exercised on macOS. On 2026-10-13, one raised-text card reached matching-job completion on an A1 through official Bambu Studio LAN printing. The package's experimental MQTT/FTPS dispatch still has offline-only evidence. Fine lettering and physical strength remain unverified; see verification for exact limits.

Related MCP server: techhand-print-fab

Install

git clone https://github.com/hyun2xyz/freecad-bambu-mcp.git
cd freecad-bambu-mcp
uv sync --frozen
cp examples/config.example.json config.local.json

Edit config.local.json. Set workspace to . when the file is in the repository root. Set printer environment variables in the local shell; credentials are never read from JSON, .env, or this repository.

uv run freecad-bambu-mcp --config config.local.json doctor
uv run freecad-bambu-mcp --config config.local.json capabilities

FreeCAD must be running with the pinned addon and its RPC server on 127.0.0.1:9875. On Windows, use .venv\Scripts\freecad-bambu-mcp.exe; macOS, Linux, and Windows share the same Python package layout.

CLI lifecycle

prepare → attach JOB sliced.3mf → review JOB SHA256 --preview-checked --hardware-checked
print JOB SHA256 --start-authorized → status JOB --refresh

preview, printer-status, control JOB pause|resume|stop --authorized, and close JOB --operator-confirmed are available. A review binds the artifact hash, hardware profile and printer target. Start dispatch is attempted at most once per job; an uncertain result holds a persistent printer lease and must be inspected rather than resent.

The MCP server exposes the same engine through stdio. examples/mcp.json is a template; replace its absolute paths locally.

Install the portable skill into your client's skill directory. Then ask, for example: “Use freecad-bambu to create an 80 × 40 × 4 mm plate with a 10 mm center hole, check the first layer, and print on my configured A1.” One request coordinates all stages and retains existing authorization; missing physical checks remain checkpoints. The package makes no LLM calls itself. Twelve compact tools, saved scripts and resumable jobs reduce repeated context and work.

Security and operator boundary

FreeCAD Python is trusted code and is disabled by default. LAN TLS verification remains enabled; use an operator-owned CA or explicitly configure self-signed trust for a trusted LAN. The package does not change security settings automatically. Keep config.local.json, credentials, job state, and sliced files private.

Development

uv run pytest

The tests are offline and do not prove hardware or physical-print behavior. See docs/setup.md, docs/research.md, and THIRD_PARTY.md.

Raised-text card example

The 90 × 50 mm card retains editable text, a folder sketch, and a rounded base in FreeCAD. Every relief intersects the 1.8 mm base by 0.1 mm before fusion; the text projects 0.8 mm above it. The example includes unmodified Roboto fonts with their Apache-2.0 license, a local wrapper for MCP execution, and the recorded design and print checks. It does not dispatch a print.