How many machines were made?
Lacking archives and numbering system of Mr. Stern's machines... this question is impossible to answer.
The machines were also sold in Germany by another business... did they have the same numbering system?
Lucio Del Piccolo's 110E is numbered 847:
Desider Stern was numbering every coffee maker, unlike Giordano Robbiati.
The Warranty papers had the same number of course written by hand.