How do I export a exporting mechanical layer? The production house says its missing. Is it an option in gerber somewhere?
When you click "Generate outputs" next to "Gerber Files", click "Configure..." then go to the layers tab. You can select any enabled layer from there.
That being said, I presume that your production house is saying that they need your outline file. To generate an outline, open your PCB file, then under the home tab, open the dropdown menu and click "Create primitives from board shape". A window should pop up asking you what layer to put your outline on, and what line thickness to use. The line thickness is irrelevant to board houses, but it helps with visuals if you make it a few mills thick.
All of the output files will be in the projects folder under: "Project name"\Default Configuration\Outputs
The boardhouse usually needs the Gerber and NC Drill files. So you can copy all the files from both into a zipped folder, then send them that. That being said, It's good to double check that the gerber files look normal in a separate program before you send them. I usually use Gerbview but the gerber viewer in KiCad works as well.
I'm using a online view that works with existing Gerber files. but this is what I see.
The add shapes I do not really understand but the main issue is the part outlines. The factory says the parts the hang over should not be part of the shape.