How to deal with bad contiguous edges for 3d printing I was trying to model my object for 3d-printing and faced this problem. I use 3D Printing Toolbox in Blender v2.79. And checking my object for manifoldness, it shows me that I have Bad Contiguous Edges. I don't know what to do with it.

On this picture, that edges are selected. And 28 Non Manifold Edges are because I haven't used Mirroring yet.
In Edit mode, I pressed A to select all, then Mesh->Normals->Recalculate Inside.
This fixed it for me as my problematic edges were inside a cylinder recess in my object.