If you are aware of any others please share.
There's a few more if you search for "rubiks cube prototype" at google, but I think it's strange that it isn't more. That's why I fears that it doesn't exist anymore, but I hope I'm wrong.
Some more question. Here's two different leaflets. Is there any more variant and why haven't they changed politechnika to politoys?
The cube to the right has a color scheme where yellow is adjacent to white. That's not the standard scheme at hungarian cubes. Could that one be one of these cubes that politoys purchased from the east in 1981?