Create a new shipping method in woocommerce 3

There were some missing things and others unnecessary. The correct way to make it work is:

add_action('woocommerce_shipping_init', 'request_shipping_quote_method');function request_shipping_quote_method() {    if ( ! class_exists( 'WC_Request_Shipping_Quote_Method' ) ) {        class WC_Request_Shipping_Quote_Method extends WC_Shipping_Method {            public function __construct( $instance_id = 0) {                $this->id = 'request_shipping_quote';                $this->instance_id = absint( $instance_id );                $this->domain = 'rasq';                $this->method_title = __( 'Request a Shipping Quote', $this->domain );                $this->method_description = __( 'Shipping method to be used where the exact shipping amount needs to be quoted', $this->domain );                $this->supports = array(                    'shipping-zones',                    'instance-settings',                    'instance-settings-modal',                );                $this->init();            }            ## Load the settings API            function init() {                $this->init_form_fields();                $this->init_settings();                $this->enabled = $this->get_option( 'enabled', $this->domain );                $this->title   = $this->get_option( 'title', $this->domain );                $this->info    = $this->get_option( 'info', $this->domain );                add_action('woocommerce_update_options_shipping_' . $this->id, array($this, 'process_admin_options'));             }            function init_form_fields() {                $this->instance_form_fields = array(                    'title' => array(                        'type'          => 'text',                        'title'         => __('Title', $this->domain),                        'description'   => __( 'Title to be displayed on site.', $this->domain ),                        'default'       => __( 'Request a Quote ', $this->domain ),                    ),                    'cost' => array(                        'type'          => 'text',                        'title'         => __('Coast', $this->domain),                        'description'   => __( 'Enter a cost', $this->domain ),                        'default'       => '',                    ),                );            }            public function calculate_shipping( $packages = array() ) {                $rate = array(                    'id'       => $this->id,                    'label'    => $this->title,                    'cost'     => '0',                    'calc_tax' => 'per_item'                );                $this->add_rate( $rate );            }        }    }}add_filter('woocommerce_shipping_methods', 'add_request_shipping_quote');function add_request_shipping_quote( $methods ) {    $methods['request_shipping_quote'] = 'WC_Request_Shipping_Quote_Method';    return $methods;}

Code goes in function.php file of your active child theme (active theme).

Tested and works.

Here the shipping method selector now displays this "Request a shipping coast" method:

Once selected and added, it's created this time:

If you edit it: