Great! 
The text gives the name of one of the three creators: it is a Herr Vogel, most probably the man on your photos. The idea to build this car arose after a visit in Western Germany in 1957 (so before the East German borders were closed). A brochure and an aluminium roof frame were all the three builders brought back from their visit. The text is not clear whether only one or three cars were built.
Two well-earned points for you.
Thank you for the extra clarification, as well as the points
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