Hi all- OK, my cute little experiment has now become a thorn in my side. I've got a model of a steel framed building that I would like printed. The original software is an architectural program (Revit) which will export to stl but it's really intended to create building plans not plastic models. I can fatten up my wall thickness to some degree in Revit but now I'm also seeing a "non fixable 800 shells" error. Before Mesh Medic was introduced, I could not even upload the whole model. The building walls and foundations were non-manifold even though they were solids to Revit. With Mesh Medic, I can at least upload the model but it does not pass further tests and is canceled. Can the shell problem be easily addressed with Blender? I'm not to keen on learning blender for the sake of this experiment. Thanks.