Loop my code 3 times? For loop

I have this code which works just fine. It adds a thumbnail of the image uploaded via a custom field to the posts list of of my custom post type in the worpdress backend. I actually have 3 custom fields which I want to add. I need a for loop I guess but I have not been able to make it work. In over my head!
My custom fields are named wpcf-upload-1-dot, wpcf-upload-2-dot, wpcf-upload-3-dot
My columns should be labeled Dot 1, Dot 2, Dot 3 so it seems I should be able to use the $i from the for loop to name and get them as I loop through???

This is my code which I have added to my themes functions.php to do one field

// Add images to the dot post list
add_filter('manage_dots_posts_columns', 'new_add_post_thumbnail_column', 6);

// Add the column
function new_add_post_thumbnail_column($cols){
$cols['new_post_thumb'] = __('Dot 1');
return $cols;

// Hook into the posts an pages column managing. Sharing function callback again.
add_action('manage_dots_posts_custom_column', 'new_display_post_thumbnail_column', 6, 2);

// Grab featured-thumbnail size post thumbnail and display it.
function new_display_post_thumbnail_column($col, $id){
case 'new_post_thumb':
$img = get_post_meta($id, 'wpcf-upload-1-dot', true);
if ($img) echo '<img src="' . $img . '" height="50" />';