Per Product Flat Rate Shipping WooCommerce

I'd like to do per product shipping programmatically. And I don't want to use the plugin. This seems like it would easy:

1. add meta field called "shipping_price" for each product.
2. hook into checkout and update shipping based off each products "shipping_price" that's in your cart

I know how to do #1. but any ideas on the best way to achieve #2?

This can be done in the following way, using get_post_meta to get the meta field 'shipping_price'

Note 1: to test this code added a line with dummy data

Note 2: Don't forget to specify the $rate->method_id

function filter_woocommerce_package_rates( $rates, $package ) {
    if ( is_admin() && ! defined( 'DOING_AJAX' ) ) return;

    // Set variable
    $cost = 0; 

    // Loop through line items
    foreach( $package['contents'] as $line_item ) {
        // Get product id
        $product_id = $line_item['product_id'];

        // Quantity
        $quantity = $line_item['quantity'];

        // Get post meta
        $shipping_price = get_post_meta( $product_id, 'shipping_price', true);

        // DEBUG, for testing purposes, REMOVE AFTERWARDS!!
        $shipping_price = 10;

        if ( $shipping_price ) {
            $cost += $shipping_price * $quantity;
        }
    }

    if ( $cost > 0 ) {
        // (Multiple)
        foreach ( $rates as $rate_key => $rate ) {

            // Targeting
            if ( in_array( $rate->method_id, array( 'free_shipping', 'distance_rate', 'table_rate' ) ) ) {
                // Set rate cost
                $rates[$rate_key]->cost = $cost;
            }
        }   

        // Single
        // Set rate cost
        // $rates['free_shipping']->cost = $cost;
    }

    return $rates;
}
add_filter( 'woocommerce_package_rates', 'filter_woocommerce_package_rates', 100, 2 );