I found this article quite interesting, amazing how things change. I'm not sure it even works but still quite fascinating what can be done.
http://bulletin.accurateshooter.com/2016/09/3d-metal-printed-rimfire-receiver-from-new-zealand/
http://bulletin.accurateshooter.com/2016/09/3d-metal-printed-rimfire-receiver-from-new-zealand/