The Pods Framework allows you to easily create custom fields (among many other things). This integration add-on lets you create facets based on Pods custom fields.

Usage

Browse to Settings > FacetWP and create a new facet.

In the facet’s “Data source” dropdown, you’ll see a new Pods header with all the fields you’ve created… just choose one of these Pods fields.

Using a Pods template

Browse to Settings > FacetWP and create a new FacetWP (shortcode) template.

When on the “Display” tab, click the “Switch to advanced mode” link on the right side. Here’s an example of what to use for the Display Code box:

<?php while ( have_posts() ): the_post(); ?>
<?php echo pods( 'your_pod_name', get_the_id() )->template( 'Your Pods Template Name' ); ?>
<?php endwhile; ?>

Finally, click on the “Query” tab to define which post type(s) to fetch, among other things.