Add Your Own Metabox To Product Screen

//Add Author Meta Boxes to Products
add_action('admin_init','foxyshop_author_details_init');
function foxyshop_author_details_init() {
    add_meta_box('foxyshop_author_details_meta', 'Extra Product Details', 'foxyshop_author_details_meta', 'foxyshop_product', 'normal', 'high');
    add_action('foxyshop_save_product','foxyshop_author_details_meta_save');
}

function foxyshop_author_details_meta() {
    global $post;
    ?>
    <div class="foxyshop_field_control">
        <label for="_author"><?php _e('Author'); ?></label>
        <input type="text" name="_author" id="_author" value="<?php echo htmlspecialchars(get_post_meta($post->ID,'_author',TRUE)); ?>" style="width: 400px;" />
    </div>

    <div class="foxyshop_field_control">
        <label for="_illustrator"><?php _e('Illustrator'); ?></label>
        <input type="text" name="_illustrator" id="_illustrator" value="<?php echo htmlspecialchars(get_post_meta($post->ID,'_illustrator',TRUE)); ?>" style="width: 400px;" />
    </div>

    <div class="foxyshop_field_control">
        <label for="_translator"><?php _e('Translator'); ?></label>
        <input type="text" name="_translator" id="_translator" value="<?php echo htmlspecialchars(get_post_meta($post->ID,'_translator',TRUE)); ?>" style="width: 400px;" />
    </div>

    <div class="foxyshop_field_control">
        <label for="_isbn"><?php _e('ISBN'); ?></label>
        <input type="text" name="_isbn" id="_isbn" value="<?php echo htmlspecialchars(get_post_meta($post->ID,'_isbn',TRUE)); ?>" style="width: 400px;" />
    </div>

    <div class="foxyshop_field_control">
        <label for="_ebook_link"><?php _e('E-book Link'); ?></label>
        <input type="text" name="_ebook_link" id="_ebook_link" value="<?php echo htmlspecialchars(get_post_meta($post->ID,'_ebook_link',TRUE)); ?>" style="width: 400px;" />
    </div>

    <div class="foxyshop_field_control">
        <label for="_kindle_link"><?php _e('Kindle Link'); ?></label>
        <input type="text" name="_kindle_link" id="_kindle_link" value="<?php echo htmlspecialchars(get_post_meta($post->ID,'_kindle_link',TRUE)); ?>" style="width: 400px;" />
    </div>

    <div class="foxyshop_field_control">
        <label for="_ibooks_link"><?php _e('iBooks Link'); ?></label>
        <input type="text" name="_ibooks_link" id="_ibooks_link" value="<?php echo htmlspecialchars(get_post_meta($post->ID,'_ibooks_link',TRUE)); ?>" style="width: 400px;" />
    </div>

    <div class="foxyshop_field_control">
        <label for="_nook_link"><?php _e('Nook Link'); ?></label>
        <input type="text" name="_nook_link" id="_nook_link" value="<?php echo htmlspecialchars(get_post_meta($post->ID,'_nook_link',TRUE)); ?>" style="width: 400px;" />
    </div>


    <?php
}

function foxyshop_author_details_meta_save($post_id) {
    global $post_id;
    foxyshop_save_meta_data('_author',$_POST['_author']);
    foxyshop_save_meta_data('_illustrator',$_POST['_illustrator']);
    foxyshop_save_meta_data('_translator',$_POST['_translator']);
    foxyshop_save_meta_data('_isbn',$_POST['_isbn']);
    foxyshop_save_meta_data('_ebook_link',$_POST['_ebook_link']);
    foxyshop_save_meta_data('_kindle_link',$_POST['_kindle_link']);
    foxyshop_save_meta_data('_ibooks_link',$_POST['_ibooks_link']);
    foxyshop_save_meta_data('_nook_link',$_POST['_nook_link']);
    return $post_id;
}