Using https://pdf-lib.js.org to make PDFs on the fly, for tight control of printout format got me from here:

to here:

…via a bunch of drafts along the way. 🙂

Unfortunately, using 9 x uncompressed 2048×2048 images per page seems to load the javascript PDF layout script pretty hard. It’s failing silently when trying to compile 3 or more pages at a time. Maybe memory overflow? Timeout? Hard to say.

I believe I need to use images of this size, because 300 DPI x 2.5 inches is… wait a minute, that’s only 750! I can use images as small as 768 x 768? Nani?! Could this be the work of an enemy DPI?

¯\_(?)_/¯

Ok, dropping a few thousand images to 768×768 size. I can always scale them back up using Real-ESRGAN. Source images were 512×512 anyway.