Use a WooCommerce product attribute taxonomy for a custom post type

cpt-case_study.php

<?php
// Register Custom Post Type
// Note: Using woocommerce_after_register_taxonomy hook instead of init because we're using a product attribute taxonomy with this CPT
function doublee_cpt_case_study() {

	$labels = array(
		'name'                  => _x('Case studies', 'Post Type General Name', 'doubleedesign'),
		'singular_name'         => _x('Case study', 'Post Type Singular Name', 'doubleedesign'),
		'menu_name'             => __('Case studies', 'doubleedesign'),
		'name_admin_bar'        => __('Case study', 'doubleedesign'),
		'archives'              => __('Case Study Archives', 'doubleedesign'),
		'attributes'            => __('Case study Attributes', 'doubleedesign'),
		'parent_item_colon'     => __('Parent case study:', 'doubleedesign'),
		'all_items'             => __('All case studies', 'doubleedesign'),
		'add_new_item'          => __('Add New case study', 'doubleedesign'),
		'add_new'               => __('Add New', 'doubleedesign'),
		'new_item'              => __('New case study', 'doubleedesign'),
		'edit_item'             => __('Edit case study', 'doubleedesign'),
		'update_item'           => __('Update case study', 'doubleedesign'),
		'view_item'             => __('View case study', 'doubleedesign'),
		'view_items'            => __('View case studies', 'doubleedesign'),
		'search_items'          => __('Search case studies', 'doubleedesign'),
		'not_found'             => __('Not found', 'doubleedesign'),
		'not_found_in_trash'    => __('Not found in Trash', 'doubleedesign'),
		'featured_image'        => __('Featured Image', 'doubleedesign'),
		'set_featured_image'    => __('Set featured image', 'doubleedesign'),
		'remove_featured_image' => __('Remove featured image', 'doubleedesign'),
		'use_featured_image'    => __('Use as featured image', 'doubleedesign'),
		'insert_into_item'      => __('Insert into case study', 'doubleedesign'),
		'uploaded_to_this_item' => __('Uploaded to this case study', 'doubleedesign'),
		'items_list'            => __('Items list', 'doubleedesign'),
		'items_list_navigation' => __('Items list navigation', 'doubleedesign'),
		'filter_items_list'     => __('Filter items list', 'doubleedesign'),
	);
	$rewrite = array(
		'slug'                  => 'case-study',
		'with_front'            => true,
		'pages'                 => true,
		'feeds'                 => true,
	);
	$args = array(
		'label'                 => __('Case study', 'doubleedesign'),
		'description'           => __('Case studies', 'doubleedesign'),
		'labels'                => $labels,
		'supports'              => array('title', 'editor', 'thumbnail', 'revisions'),
		'taxonomies'            => array('case_study_category', 'pa_industry'),
		'hierarchical'          => false,
		'public'                => true,
		'show_ui'               => true,
		'show_in_menu'          => true,
		'menu_position'         => 5,
		'menu_icon'             => 'dashicons-format-aside',
		'show_in_admin_bar'     => true,
		'show_in_nav_menus'     => true,
		'can_export'            => true,
		'has_archive'           => true,
		'exclude_from_search'   => false,
		'publicly_queryable'    => true,
		'rewrite'               => $rewrite,
		'capability_type'       => 'post',
	);
	register_post_type('case_study', $args);

}
add_action('woocommerce_after_register_taxonomy', 'doublee_cpt_case_study', 0);


// Enable post edit metabox for pa_industry taxonomy
function doublee_case_study_pa_industry($args, $taxonomy) {
	if ('pa_industry' === $taxonomy) {
		$args['meta_box_cb'] = 'post_categories_meta_box';
	}

	return $args;
}
add_filter('register_taxonomy_args',  'doublee_case_study_pa_industry', 10, 2);