I'm trying to display multiple pictures of OTHER products in product_listing.php

The reason I'm doing this, is because the other products are included in the kit / set of the main product. I've managed to pull the variable of the $product_image for each of the related part #'s but I'm still figuring out how to display those images dynamically.

I have a variable called: $products_image
and a bunch of files in zen cart:

(thumbnails)
images\star_wars\chewbacca.jpg
images\star_wars\chewbacca_01.jpg
images\star_wars\chewbacca_02.jpg
images\star_wars\chewbacca_03.jpg

(large images)
images\large\star_wars\chewbacca_lrg.jpg
images\large\star_wars\chewbacca_01_lrg.jpg
images\large\star_wars\chewbacca_02_lrg.jpg
images\large\star_wars\chewbacca_03_lrg.jpg

Code:
$products_image=chewbacca.jpg
How could I make a dynamic array to run "file_exists" on the chewbacca images, or images in other directories setup in the same manner. If the file exists, I would like to display it's image.

Code:
<img src="$products_image">