The Customize User Interface (CUI) Editor is used to customize the user interface of AutoCAD. Before you start customizing your own menus, toolbars, and other user interface elements, you should familiarize yourself with the customization environment.
Manage tab
Customization
panel
User
InterfaceTo open the Customize
User Interface Editor, enter cui at the Command
prompt. Once the Customize User Interface
(CUI) Editor is opened, view the contents of the loaded customization
files by expanding the elements in the tree structure, and view
the properties of the elements by selecting them.
Select the Transfer tab to see how to migrate or transfer customizations; select the Customize tab to see how to create or modify user interface elements.
Once you are familiar with the environment, you can start to take advantage of the capabilities of the tools. For more information about the improved customization capabilities, see How Customization Has Changed.
Following is an example of the Customize User Interface (CUI) Editor, Customize tab. You use this tab to customize interface elements in CUIx files.

Customize the user interface to make the drawing environment specific to certain types of tasks. For example, if you want a toolbar that contains the commands you use most often, you can create a new Favorites toolbar in the Customize User Interface (CUI) Editor and then load the new toolbar in AutoCAD.