Custom product slider from woocommerce products

Question

I want to create a custom products slider for my woocommerce theme. I want to retrieve the thumbnails from my products with a custom taxonomy (product_tag) for example "t-shirt".

I'm calling the "product_tag" like this :

<?php
 $categories = get_terms( 'product_tag', 'orderby=count&hide_empty=0' );

 $count = count($categories);
 if ( $count > 0 ){
     echo "<ul>";
     foreach ( $categories as $categories ) {
       echo "<li>" . $categories->name . $categories->count . "</li>";

     }
     echo "</ul>";
 }
     ?> 

But how can I get the URL thumbnails from this product_tag?

Something like wp_get_attachment_url( $id ) but for products?