BrickGen - Rebrickable > LDraw > LDview > STL/3mf (3D Printing) Generator

BrickGen is a self-hosted web application that generates print-ready STL files for sets from Rebrickable. Search for any set via Rebrickable, and it automatically fetches the parts list with LDraw IDs, converts each brick to STL format using the official LDView tool, and generates a ZIP file with all individual STL files ready for your slicer.

Features

• Authentication: JWT-based authentication system for secure access
• Set Search: Search sets by name or number using the Rebrickable API
• Automatic Part Conversion: Converts LDraw .dat files to STL using official LDView tool
• ZIP Download: All individual STL files packaged for easy import to any slicer
• Part Numbering: Duplicate parts numbered (3007_1.stl, 3007_2.stl, etc.)
• Job Tracking: Background processing with real-time progress updates
• Caching: Aggressive caching of API responses and converted STLs for speed
• 100% Success Rate: LDView properly handles all LDraw parts including sub-files

Technology Stack

Backend:

• Python 3.13+ with FastAPI
• SQLite for caching and job tracking
• LDView CLI tool for LDraw → STL conversion
• LDraw parts library (10,000+ parts)
• Key dependencies: fastapi, uvicorn, aiohttp, sqlalchemy, pydantic, numpy, numpy-stl

Frontend:

• React 18 with Vite
• TailwindCSS for styling
• React Router for navigation

Infrastructure:

• Single Docker container (multi-stage build)
• Docker Compose for local deployment
• Kubernetes-ready with health checks

Quick Start

Prerequisites

• Docker and Docker Compose installed
• Rebrickable API key from: Rebrickable

Installation

1. Clone the repository

   git clone <repository-url>
   cd brickgen

2. Configure environment

   cp .env.example .env
   # Edit .env and set your values:
   # - Your Rebrickable API key (required)
   # - Authentication credentials (default: brickgen/brickgen)
   # - A secure JWT secret key (recommended for production)

   Note: Default credentials are brickgen/brickgen. You'll see a warning on startup if you use defaults. Consider changing them for production deployments.

3. Build and run with Docker Compose

   docker-compose up -d

4. Access the application

   Open your browser to http://localhost:8000

   You'll be prompted to log in with the credentials you set in .env

   See AUTHENTICATION.md for detailed authentication documentation.

First Run

On first startup, the application will automatically download the LDraw parts library (~100MB). This may take a few minutes. You can monitor progress in the logs:

docker-compose logs -f brickgen

Usage

1. Search for a set by name or number
2. Select a set from the search results
3. Configure build plate dimensions (defaults to 220x220mm)
4. Click "Generate 3MF File" and wait for processing
5. Download the generated 3MF file when complete
6. Slice the 3MF file in your preferred slicer (PrusaSlicer, Cura, etc.)
7. Print!

3MF and slicers

• Multiple build plates: If parts don’t fit on one plate, Brickgen adds more logical plates (stacked in Y) in the same 3MF so everything is packed.
• Colors: Part colors from Rebrickable are written into the 3MF (Materials Extension) so slicers can show colored parts.
• Bambu Studio: When you open a 3MF that wasn’t created by Bambu Lab, Bambu may show “load geometry data and color data only” and can ignore placement, so parts may appear stacked in the center. Use the slicer’s own “Arrange” or placement tools if needed. Other slicers that support 3MF Core (e.g. PrusaSlicer, Cura) should respect the packed placement.

Configuration

Build Plate Defaults

Edit .env file or use the Settings page in the UI:

DEFAULT_PLATE_WIDTH=220    # mm
DEFAULT_PLATE_DEPTH=220    # mm
DEFAULT_PLATE_HEIGHT=250   # mm
PART_SPACING=2             # mm spacing between parts

Common Printer Presets

• Bambu Lab X1 Carbon: 250mm^3
• Bambu Lab A1 Mini: 180mm^3

Development

Running Locally (without Docker)

Prerequisites:

# Install pipenv if not already installed
pip install --user pipenv

Backend: (run from project root so the backend package resolves)

cd backend
pipenv install --dev
cd ..
pipenv run --path backend uvicorn backend.main:app --reload

Or activate the virtual environment from project root:

pipenv shell --path backend
# from project root (brickgen/)
uvicorn backend.main:app --reload

Run tests: (use the venv; do not use --system locally)

pipenv run --path backend python -m pytest backend/tests -v --tb=short

Database migrations: The app uses Alembic. Migrations run automatically on startup (alembic upgrade head). To run or inspect migrations manually (from project root, with the same DATABASE_PATH or .env in use):

cd backend && pipenv run env PYTHONPATH=/path/to/brickgen bash -c 'cd /path/to/brickgen && alembic upgrade head'

If you have an existing database that was created before migrations were added (e.g. with the old create_all + inline ALTERs), run once to mark it as up to date without re-running migrations:

alembic stamp head

Then future startups will run upgrade head as a no-op. You can view applied migrations and table row counts in Settings → Database in the UI.

Frontend:

cd frontend
npm install
npm run dev

Project Structure

brickgen/
├── backend/
│   ├── api/
│   │   ├── integrations/    # API clients (Rebrickable, LDraw)
│   │   └── routes/          # FastAPI routes
│   ├── core/                # Core processing logic
│   │   ├── ldview_converter.py
│   │   ├── stl_processing.py
│   │   ├── stl_orientation.py
│   │   ├── stl_render.py
│   │   └── threemf_generator.py
│   ├── models/              # Pydantic schemas
│   ├── config.py            # Configuration
│   ├── database.py          # SQLAlchemy models
│   └── main.py              # FastAPI app
├── frontend/
│   └── src/
│       ├── components/      # React components
│       ├── pages/           # Page components
│       └── App.jsx
├── Dockerfile               # Multi-stage build
├── docker-compose.yml
└── README.md

API Endpoints

• GET /api/search?query={name} - Search Rebrickable sets
• GET /api/sets/{set_num} - Get set details
• POST /api/generate - Generate 3MF/STL (legacy)
• GET /api/projects - List projects
• POST /api/projects - Create project
• GET /api/projects/{project_id}/jobs - List jobs for a project
• POST /api/projects/{project_id}/jobs - Create job (generate 3MF/STL)
• GET /api/jobs/{job_id} - Check job status
• GET /api/download/{job_id} - Download 3MF or ZIP file
• GET /api/settings - Get settings
• POST /api/settings - Update settings
• GET /health - Health check

Troubleshooting

LDraw Library Download Fails

The application automatically downloads the LDraw library on first run. If it fails:

1. Check your internet connection
2. Manually download from https://library.ldraw.org/library/updates/complete.zip
3. Extract to ./data/ldraw/ directory
4. Restart the application

No Parts Found for Set

Some sets may not be available in Rebrickable's database. Try:

1. Ensuring the set number is correct (e.g., "75192-1")
2. Checking if the set exists on https://rebrickable.com

STL Conversion Failures

Not all LDraw parts may convert successfully. The application will:

1. Log warnings for failed conversions
2. Continue processing available parts
3. Generate 3MF with successfully converted parts

Roadmap

Phase 1 - Initial MVP (Done)

• Provide a simple web interface that can be used to go from Rebrickable set to a zip file containing part STLs and/or 3mf file with part color info and bin packed placement.

Phase 2 - Enhancements

• Allow the import of full LDraw mpd files.

• Support external postgres database.

• Quick import of users saved MOCs, Sets and Parts from Rebrickable.

• Support Brickset API.

Contributing

Contributions are welcome! Please feel free to submit issues or pull requests.

License

MIT License - see LICENSE file for details

Acknowledgments

• LDraw - CAD parts library
• LDView - LDraw viewer and STL export (included under its MIT license option)
• Rebrickable - Set search and parts inventory
• 3MF specification - 3MF file format (BrickGen generates 3MF in-house; no lib3mf dependency)

For the full list of third-party software and licenses, see ATTRIBUTIONS.md.

Disclaimer

LEGO® is a trademark of the LEGO Group, which does not sponsor, authorize, or endorse this application. This tool is for personal use only. Please respect LEGO's intellectual property rights.