original.php

<?php
/**
 * deargodwhy Metabox
 * 
 * @package deargodwhy
 */

add_action( 'add_meta_boxes', 'deargodwhy_add_sidebar_layout_box' );

function deargodwhy_add_sidebar_layout_box(){
    add_meta_box( 
        'deargodwhy_sidebar_layout',
        __( 'Sidebar Layout', 'deargodwhy' ),
        'deargodwhy_sidebar_layout_callback', 
        'page',
        'normal',
        'high'
    );
}


$deargodwhy_sidebar_layout = array(
                        'right-sidebar' => array(
                             'value'=> 'right-sidebar',
                             'label'=> __( 'Right Sidebar(default)', 'deargodwhy'),
                             'thumbnail'=> get_template_directory_uri() . '/images/right-sidebar.png'         
                         ),
                        'no-sidebar' => array(
                             'value' => 'no-sidebar',
                             'label' => __('No Sidebar','deargodwhy'),
                             'thumbnail'=> get_template_directory_uri() . '/images/no-sidebar.png'
                        )
    );

function deargodwhy_sidebar_layout_callback(){
    global $post , $deargodwhy_sidebar_layout;
    wp_nonce_field( basename( __FILE__ ), 'deargodwhy_nonce' );
?>
 
<table class="form-table">
    <tr>
        <td colspan="4"><em class="f13"><?php esc_html_e( 'Choose Sidebar Template', 'deargodwhy' ); ?></em></td>
    </tr>

    <tr>
        <td>
        <?php  
            foreach( $deargodwhy_sidebar_layout as $field ){  
                $layout = get_post_meta( $post->ID, 'deargodwhy_sidebar_layout', true ); ?>

            <div class="radio-image-wrapper">
                <label class="description">
                    <span><img src="<?php echo esc_url( $field['thumbnail'] ); ?>" alt="" /></span><br/>
                    <input type="radio" name="deargodwhy_sidebar_layout" value="<?php echo esc_attr( $field['value'] ); ?>" <?php checked( $field['value'], $layout ); if( empty( $layout ) && $field['value']=='right-sidebar'){ checked( $field['value'], 'right-sidebar' ); }?>/>&nbsp;<?php echo esc_html( $field['label'] ); ?>
                </label>
            </div>
            <?php } // end foreach 
            ?>
            <div class="clear"></div>
        </td>
    </tr>
</table>
 
<?php 
}

/**
 * save the custom metabox data
 * @hooked to save_post hook
 */
function deargodwhy_save_sidebar_layout( $post_id ){
    global $deargodwhy_sidebar_layout , $post;

    // Verify the nonce before proceeding.
    if ( !isset( $_POST[ 'deargodwhy_nonce' ] ) || !wp_verify_nonce( $_POST[ 'deargodwhy_nonce' ], basename( __FILE__ ) ) )
        return;
    
    // Stop WP from clearing custom fields on autosave
    if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE)  
        return;

    if ('page' == $_POST['post_type']) {  
        if (!current_user_can( 'edit_page', $post_id ) )  
            return $post_id;  
    } elseif (!current_user_can( 'edit_post', $post_id ) ) {  
            return $post_id;  
    }


    foreach( $deargodwhy_sidebar_layout as $field ){  
        //Execute this saving function
        $old = get_post_meta( $post_id, 'deargodwhy_sidebar_layout', true ); 
        $new = sanitize_text_field( $_POST['deargodwhy_sidebar_layout'] );
        if ( $new && $new != $old ) {  
            update_post_meta($post_id, 'deargodwhy_sidebar_layout', $new );  
        } elseif ('' == $new && $old ) {  
            delete_post_meta( $post_id,'deargodwhy_sidebar_layout',  $old );  
        } 
     } // end foreach     
}
add_action('save_post' , 'deargodwhy_save_sidebar_layout');