Histogramming all 50-ish resonator frequencies shows reasonably good distributions:
I don’t know what to make of the difference between the parallel and serial resonant frequencies for each tuning fork:
Perhaps each resonator’s frequency depends on its (laser-trimmed) tine mass and follows a more-or-less normal distribution, but the parallel-serial difference depends on (well-controlled) etched dimensions producing quantized results from three different masks / wafers / lots?
For reference, the resonators look like this:
Producing the histograms uses the LibreOffice
frequency() array function, which requires remembering to whack
Ctrl-Shift Enter to activate the function’s array-ness.