I am wondering if there is a way, after customizing the AEM Designer UI, palettes basically, and then being able to export that customization so that other users can get the same setup.
I am thinking there has to be a config file somewhere...
You can go to location C:\Users\username\AppData\Roaming\Adobe\Designer\6.5 as mentioned by @radzmar and share file InspectorsEN193.xml with any other user to import your UI settings.
The user should replace existing file with the new one and then open the designer to see customized UI