Kdjykuj

I am trying to create a shipping rule in magento. In this rule I need some functionality like $50 per 3 products will add as shipping rule. If someone added 4 items to 6 items in cart, then the shipping charges should $100 ($50 for first 3 pair of items and other $50 for remain items).

But i am stuck and didn't found any extension or solution for this.

Magento 1

Follow this tutorial to create custom shipping method

in config.xml

<default>

        <carriers>

            <customshipping>

                <active>1</active>

                <model>customshipping/carrier_customshipping</model>

                <name>Custom Shipping</name>

                <title>Custom  Shipping </title>

                <description>50 Shipping cost per 3 item</description>

                <sort_order>1</sort_order>

            </customshipping>

        </carriers>

</default>

create shipping model class

<?php  

    class Stackexchange_Customshipping_Model_Carrier_Customshipping     

        extends Mage_Shipping_Model_Carrier_Abstract

        implements Mage_Shipping_Model_Carrier_Interface

    {  

        protected $_code = 'customshipping';  



        /** 

        * Collect rates for this shipping method based on information in $request 

        * 

        * @param Mage_Shipping_Model_Rate_Request $data 

        * @return Mage_Shipping_Model_Rate_Result 

        */  

        public function collectRates(Mage_Shipping_Model_Rate_Request $request){  

            $result = Mage::getModel('shipping/rate_result');



             if ($request->getAllItems()) {

                $count=0;

                foreach ($request->getAllItems() as $item) {

                    $count+=$item->getQty();

                }

                $count=ceil($count/3);

                $method = Mage::getModel('shipping/rate_result_method');  

                $method->setCarrier($this->_code);  

                $method->setCarrierTitle($this->getConfigData('title'));

                $method->setMethod($this->_code);  

                $method->setMethodTitle($this->getConfigData('name'));

                $method->setPrice($count*50);

                $method->setCost($count*50);

                $result->append($method);  

            }

            else

            {

                $error = Mage::getModel('shipping/rate_result_error');

                $error->setCarrier($this->_code);

                $error->setCarrierTitle($this->getConfigData('name'));

                $error->setErrorMessage('Shipping Method is not available');

                $result->append($error);

            }

            return $result;

        }  



        /**

         * Get allowed shipping methods

         *

         * @return array

         */

        public function getAllowedMethods()

        {

            return array($this->_code=>$this->getConfigData('name'));

        }

    }  

Created module for you.