Generating List of Tags from Custom Post Type

If all you’re looking to do is list out the model tags as list items, this should work for you:

$terms = get_the_terms( $post->ID, 'model_tag' );
if ( $terms && ! is_wp_error( $terms ) ) :
    $model_tags="<ul>";
    foreach ( $terms as $term ) {
        $model_tags .= '<li>' . $term->name . '</li>';
    }
    $model_tags .= '</ul>';

    echo $model_tags; ?>
endif;