Blender stl file inversed in Simplify3D

[petersmall]

I've created a nine compartment tray with Blender 2.8. When I export the STL and open it with Simplify3D is shows the inverse (the sides are empty spaces and the insides of the compartments are shown as being filled). Where am I going wrong? Any suggestions would be gratefully appreciated.

[S3D-Alex]

Could you please post a Factory File or even just the STL you reference so we can take a closer look?

[reddadsteve]

Blender has an add-on called PRINT3D that helps analyze meshes for being manifold. Have you looked at that?

One possible issue you may have is with the normals facing the wrong way. Select everything in edit mode and do crtl-n to reverse the normals.

Teamwork,
Steve