The idea of perfecting this project is rapidly consuming me.

Making the board slightly bigger (38x59 mm) makes it fit very nicely into a Hammond extruded aluminum case, just like my GPSDO. And like that project, I can probably design a pair of PCBs to fit into the ends with the correct perforations for the jacks and the error LED light pipe. I still can't match the Amazon price point selling them on Tindie, but I pretty much put that down to volume. I can get them down to a retail-plus-free-US-shipping price of about $20 for the board, $20 for the case, and $10 for a power supply. That's at least not Fred Falvy levels of price foolishness.