Add a Font Awesome icons select to CPT meta by humanmade: https://github.com/humanmade/Custom-Meta-Boxes/

gistfile1.txt

class ah_is_awesome {

	function __construct() {

		if(! class_exists( 'CMB_Meta_Box' ) ) {
			require_once( 'includes/custom-meta/custom-meta-boxes.php' );
		}

	}
	
	function font_awesome_array() {
		
		$pattern = '/\.(fa-(?:\w+(?:-)?)+):before\s+{\s*content:\s*"(.+)";\s+}/';
		$subject = file_get_contents(plugin_dir_url( __FILE__ ) . 'css/style.css');

		preg_match_all($pattern, $subject, $matches, PREG_SET_ORDER);

		$icons = array();

		asort($icons);

		foreach($matches as $match){
		    $icons[$match[1]] = $match[1];
		}

		return $icons;
	}
	
	function custom_meta( array $meta_boxes ) {

		$meta_boxes[] = array(
	        'title' => 'Meta Options',
	        'pages' => 'ah_resume_skill', //Your custom post type
	        'fields' => array(

				array( 
					'id'      => 'icon', 
					'name'    => __( 'Select icon', 'audio-player' ), 
					'type'    => 'select', 
					'cols'	  => 6,
					'options' => $this->font_awesome_array()
				),
			),
	    );

	    return $meta_boxes;

	}
}