STL to LEGO Converter

A Python application that converts 3D models (STL files) into buildable LEGO sculptures. The project currently supports converting 3D models into voxelized representations, with planned features to generate LEGO building instructions.

Features

Currently Implemented

• User-friendly GUI for file selection and conversion
• STL file loading and processing
• Advanced voxelization with optimized resolution
• Exports both .npy (NumPy array) and voxelized STL files
• Automatic resolution calculation based on model complexity
• Multi-threaded processing for responsive UI

Planned Features

• LEGO brick mapping algorithm
• Generation of building instructions
• LDraw file export for compatibility with LEGO CAD software
• Optimization for structural stability
• Color matching for colored STL models

How It Works

1. Voxelization Process

Original 3D model input

The voxelization process converts a smooth 3D model into discrete cubic volumes

The current implementation uses a sophisticated voxelization technique:

1. Surface Sampling:

   • The 3D model's surface is sampled using an optimized grid
   • Sub-voxel sampling points ensure accurate surface representation
   • Adaptive resolution based on model complexity

2. Volume Processing:

   • Surface voxels are identified through triangle-point proximity tests
   • Internal volumes are filled using flood-fill algorithms
   • Floating voxels are removed for model integrity

3. Optimization:

   • Binary morphological operations smooth the result
   • Connected component analysis ensures model coherence
   • Memory-efficient batch processing for large models

2. Future LEGO Conversion

Example of a LEGO sculpture

The planned LEGO conversion will:

1. Brick Mapping:

   • Convert voxels into optimal LEGO brick combinations
   • Consider standard LEGO brick sizes (1x1, 2x2, 2x4, etc.)
   • Ensure structural stability through proper brick overlapping

2. Structure Optimization:

   • Analyze structural integrity
   • Optimize brick layout for stability
   • Add support structures where necessary

3. Instruction Generation:

   • Create layer-by-layer building instructions
   • Generate LDraw format files for LEGO CAD compatibility
   • Provide brick inventory and color matching

Installation

# Clone the repository
git clone https://github.com/yourusername/stl-to-lego-converter.git

# Install dependencies
pip install -r requirements.txt

Usage

1. Run the application:

python main.py

2. Use the GUI to:
   • Upload your STL file
   • Click "Convert to LEGO!" to process
   • Find output files in the same directory as input

Output Files

The converter currently generates two files:

• {model_name}.npy: NumPy array of voxel data
• {model_name}_voxelized.stl: Voxelized 3D model for visualization

Requirements

• Python 3.8+
• numpy
• scipy
• numpy-stl
• tkinter

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.