This prototype was found in a huge skip of parts that were either unused or destined to be scrapped back in the mid-80's (from the bulgarian Mikro '67 factory):








While the pics are not mine (but I can request more if needed); I'm doing a favor of a friend who has all these parts with him currently and he's willing to sell them all. But before that we'd like to hear suggestions and possibly some more info about it as it is extremely unusual find!I personally suspect it could be one of these samples sent to the factory back then.
If you would like to express interest, offer or just have more information about the rest of the parts repository, please PM me.