Now that the principles are working and well understood, it's time to make a PCB.
The diode ROM uses a bit more space than I initially thought but I managed to keep it pretty compact. However the issue occurs in the other dimension: the diodes add about 3mm of thickness to the stack.
The IV9's diameter is 10.5mm while the RES15 is 11mm. Add the diodes, the PCB thickness and the unavoidable clearance to prevent shorting the diodes' leads to the next board's RES15 metallic can, and the board pitch is 18mm. So each IV9 is separated by a 8mm gap...
Anyway I've decided to move forward and try to run a first layout through @oshpark (Thanks guys !) before I build a few dozens of modules. I might have to buy a few more thousands of diodes though :-D
The PCB is just a bit larger than 8cm and a little over 7cm high. Enjoy the view !
The approach is a bit modified : either the module is used "standalone", or the outputs can be broken out to a more conventional display panel (with a smaller pitch for a nice aspect). The connector shapes are temporary but should work nicely for the first attemps.
I am excited to receive the first purple boards :-D Notice however that I have routed the board as if I had to etch it myself or with DIY, lousy resolution, processes. Just like "in the old good days" of perchlo baths with dubious concentration and temperature. I'm ashamed to ask @oshpark to build these because I wanted to use their high quality process... But I couldn't wait this time.