$args = array(
    'post__in' => array(43,23,65)
);

$posts = get_posts($args);

foreach ($posts as $p) :
    //post!
endforeach;

$args = array(
    'post_type' => 'pt_case_study',
    'post__in' => array(2417, 2112, 784)
);

$posts = get_posts($args);