# How to fix inconsistent surface Normals of a shape in Blender?

I have a 3D shape whose surface Normals seem not to be consistent. It looks like the image below after rendering. It seems that the Normals are not consistent for this shape. I have tried Solidify and Subdivision Surface modifiers but they seem not to work (or I'm not setting their parameters correctly). I wonder how I can resolve this issue. Any help would be appreciated. Here you can find the 3D shape.