@alexpacio2013 said in Discussion - object is not a manifold solid !?: I guarantee you that Bool tools 2 works and works better than the standard tools even among solids You're preaching to the choir on that point. I don't use nor even recommend the native Solid Tools. I guess I have no problem, even for complex objects, with making them solids so I get predictable results when using Bool Tools 2 or Eneroth Solid Tools.