The user should create a new customization xml-file. This can be done via the pull-down menu Tools-->Customize Interface... (Command CUSTOMIZE).
In this new customization the user can create new toolbars and save them in a separate XML customization. See also the attached images Add_New_Customization.png and Add_New_Toolbar.png
The resulting path of the new user xml customization file is displayed in the dialog before the creation. By default it is saved under Users/[Current user]/Library/Preferences/ARES Commander Edition/x.x.xxx/UI . The user can copy the xml-file into the other users folder Users/[user XY]/Library/Preferences/ARES Commander Edition/x.x.xxx/UI .
An Additional Note:
When you had created new customization file, you have to selected it as Source again, so that your new toolbars are saved into this new xml-file.
Then the new user can load the new customization via the LOADCUSTOMIZATION command in the CAD application and add it to its current loaded customization files.
Copy and Paste of existing toolbars between two customization files is not possible at the moment. You have to create the toolbar or menu entries for each customization xml separately.