To fix peeling in STL file 3D models, address non-manifold edges (edges with wrong face counts) or inverted normals—these cause the surface gaps that look like peeling. Use free tools like Meshmixer’s “Auto Repair” for quick basic fixes, or Blender to recalculate normals (via “Recalculate Outside”) or make the mesh manifold. If you’re new, start with Meshmixer’s one-click repair; for tough cases, use Blender to manually adjust edges or normals step-by-step.
