* replaced the USB micro-B connector with USB-C
* added two-pin headers to daisy-chain power between multiple boards
* one design can be built to charge either AAs or AAAs, depending on which battery terminals you buy
* used mostly SMD components so most of the assembly work can be farmed out
I have designed a 3D-printable mount that can be screwed together in as large a charging array as you need.. Dead batteries can be snapped in and freshly-charged, topped-off batteries can be snapped out as needed.
The first iteration had the batteries too close together, so you couldn't actually put four AAs on it. Those will still be usable for AAAs, as shown in the photo: v1 configured for AAAs on the bottom row, v2 configured for AAs on the top row.
What I'm calling "v1" here is tagged in the Git repo as "v0.1." What I'm calling v2 here is referred to in some commits as "v1.1", and is also (as of now) master. Hopefully that's as clear as mud. :)
A printable frame is now included in the frame subdirectory of the Git repo (OpenSCAD source and STL included). It's assembled mostly with M3x12 screws and nuts (had to step up to M3x16 for the vertical connections between frames) and can be extended as far as you need to go. It accommodates both v1 and v2 boards (probably a capability only I will need, unless someone else built v1 that I don't know about).