One of the interesting challenges of vintage Hamiltons is trying to identify models you haven't seen before. There are several well documented models that were not shown in the catalogs but were shown in advertisements in magazines and such. Other times models were potentially made for other markets, like Europe or South America. Hamilton produced unique models to be used as awards and presentations - these are often easy to identify when they say "masterpiece" on the dial. Lastly there was a line of men's and women's models that were sold through a large national retailer and were identified by their M-series and F-series names. Not all M-series models are well-documented but one clue is they typically came in a red clamshell case.
Anyway, I recently received a watch for repair that doesn't appear to be cataloged. It might go solely by the case id of 64046-3.
Case numbers are interesting. Sometimes they mean something and other times they don't reveal too much. For example, the -3 typically denotes a stainless steel case. Often (but not always) the first two digits represents the caliber of the movement inside. So this model likely has a caliber 64 inside. Sometimes the last two digits represents the year it was introduced - that is not the situation here though. There's no one-size-fits-all nomenclature or rationale for model numbers.
My project watch appears to be in good shape but it definitely could use a new crystal.