Portal In Itself

The question what happens if you put a portal into itself has become a meme with moderate popularity. Yet, Im aware of only two examples trying to answer that question. One example is a video (Portal through Itself - MinutePhysics). While this is certainly a great video, due to the passive nature of a video one cannot explore these portals by themself. The other example is Portal through Itself - Optozorax. I know this program was available in the past, but somehow I cant find it anywhere, anymo...