Use tools like or Blender to "close" any holes in the mesh. A solid model must have a completely enclosed surface with no gaps (often called "manifold"). Hello how can i turn SDFA file to STL file - Facebook
If you are using , there is a known native loophole to extract the meshes: Generate or open any standard order. Switch to Expert Mode . Open or load the .sdfa file you wish to convert. Sdfa File To Stl