This is a demo of the WooCommerce Product Configurator plugin. The Image to the left is built up using 20 transparent PNG layers. Without WooCommerce Product Configurator, you would need 165 final images to achieve the same effect; not to mention the pain it would cause to add another colour option to mix.
The colour and image swatches were create using WooCommerce Attribute Swatches.
Watch Credit: Timex