This is for the BeamNG developers only.

To add new icons in the editor icon atlas, you need to contact an artist who can help with creating your new icon. The icon will be created as a SVG and placed in an art folder that will be read by a compilation step which will generate the atlas PNG file with all the editor icons. We encourage you find an already available icon for your operation in the current list. To see what icons are available for use within the editor UI, you can use the menu Tools->Experimental->Icons tool.

For Lua programmers, editor.icons table contains all the available icons.