Programmatically get a form in Drupal 8
This renders within a block plugin:

class myModule extends BlockBase {
  public function build() {

    $default_form = \Drupal::config('contact.settings')-&gt;get('default_form');
    $entity = \Drupal::entityManager()-&gt;getStorage('contact_form')-&gt;load($default_form);

    $message = \Drupal::entityManager()
      -&gt;getStorage('contact_message')
      -&gt;create(array(
        'contact_form' =&gt; $entity-&gt;id(),
      ));

    $form = \Drupal::service('entity.form_builder')-&gt;getForm($message);

    return $form;
  }
}