Some time ago I have found a GOMZ-Sport camera with very uncommon viewfinder extension. It seems to be professional made, but unfortunately I have no information, whether such extensions were made by GOMZ. May be it was simply made by some photo-enthusiast .
This excellent "extra" part is certainly made by a leathe expert. It is ot original for sure. It is applied in this camera because the original owner should have a near sight vision and the piece corrects the focus without the need of an extra lens. Regards LP