How about an SiO2 slide rule? Right out of the corporate libertarian box.
http://www.nzeldes.com/HOC/ALKU.htm
One can only guess, and the likely reason would be post-war shortages. This slide rule was made around 1947; it is quite likely that the woods used in this industry (carefully selected for long-term dimensional stability) were not readily available in East Germany at that time, and perhaps neither was the machining equipment needed to produce metal slide rule parts. But plate glass is abundant, is flat and dimensionally stable, and can be cut to fairly good precision.
Alfred Kuhmann may have been practicing my favorite definition of Engineering: “The art of making what you want from things you can get”.
And just think...it's from a Communist country! OMG!
