Product Add-ons @ Single Product Page

 /**

 * @snippet       Product Add-ons @ Single Product Page

 * @how-to        Get CustomizeWoo.com FREE

 * @sourcecode    https://businessbloomer.com/?p=111758

 * @author        Rodolfo Melogli

 * @compatible    WooCommerce 3.5.4

 * @donate $9     https://businessbloomer.com/bloomer-armada/

 */

 

add_action( 'woocommerce_before_add_to_cart_quantity', 'bbloomer_gift_wrap', 35 );

   

function bbloomer_gift_wrap() {   

   ?>

   <label><input type="checkbox" name="gift-wrap" value="Yes">$2 Gift Wrap?</label>

    <?php

}

   

add_filter( 'woocommerce_add_cart_item_data', 'bbloomer_store_gift', 10, 2 );

   

function bbloomer_store_gift( $cart_item, $product_id ) {

   if( isset( $_POST['gift-wrap'] ) ) $cart_item['gift-wrap'] = $_POST['gift-wrap'];

   return $cart_item;

}

 

add_action( 'woocommerce_cart_calculate_fees', 'bbloomer_add_checkout_fee' );

  

function bbloomer_add_checkout_fee() {

   foreach ( WC()->cart->get_cart() as $cart_item_key => $cart_item ) {

        if ( isset( $cart_item['gift-wrap'] ) ) {

            $itsagift = true;

            break;

        }

    }

    if ( $itsagift == true ) WC()->cart->add_fee( 'Gift Wrap', 2 );

}