Metabox DOS

<?php $images = rwmb_meta( 'my_field_id', ['size' => 'thumbnail'] ); ?>
<h3>Uploaded images</h3>
<ul>
    <?php foreach ( $images as $image ) : ?>
        <li><img src="<?= $image['url']; ?>"></li>
    <?php endforeach ?>
</ul>
Juan Jose Gonzalez