Free tools for converting STL 3D models include open-source options (MeshLab, Blender) and online platforms (Convertio, Windows 3D Builder).
- **MeshLab**: Best for basic mesh fixes (like repairing gaps) and quick conversions to OBJ/FBX. - **Blender**: Mixes advanced model editing (e.g., resizing, smoothing) with STL conversion—great if you need to tweak files first. - **Online tools (Convertio, Windows 3D Builder)**: No download required; ideal for fast, simple tasks.
For beginners, start with Convertio (easy online use) or Blender (free editing + conversion)—both are user-friendly and free.