function sl_cc_printus_extra_template_data_070324($extra, $order, $template_name){
return $extra . '<br/><strong>Shipping method:</strong> ' . $order->get_shipping_method();
}
add_filter('printus_template__extra_data', 'sl_cc_printus_extra_template_data_070324', 12, 3);
The printus_template__extra_data
filter can be used to add other custom data to the prints.