Q. Who invented silver etrog boxes?
When etrogim were rare and difficult to obtain – central and northern Europe derived them from Mediterranean countries and sometimes the regimes charged huge sums for permission to bring in lulavim and etrogim – communities exercised great care in storing their etrogim when they were not in use during the actual services.
There was also a rabbinic rule that every mitzvah had to be beautified, so every appurtance had an ornamented cover or receptacle.
Generally etrog boxes were made of silver with appropriate adornment; some families had etrog boxes made of olive wood from the Holy Land.