After all that (and then some) I still needed to make a physical printed circuit board. That meant more fun with KiCad, which I do like pretty well.  I spent a lot of time hunting down component parts and footprints and such - definitely on my faves list.  But I somehow managed to produce something that OSH Park could manufacture:

I'm sure some layout guys are busily sharpening their knives and I know there's much, much, much I don't know. My defense:

I came,

I saw,

I hacked,

Deal.  ;-)

One particular challenge was placement of the connectors to which the NeoPixel rings attach. I had to bumble around in Eagle enough to understand how the power and data connectors were placed in its coordinate frame and then translate that into KiCad's. I still have bruises on my scalp from standing on my head (and in the end I had to pretty much just guess on the additional ring-24 power and grounds). I whipped up yet another spreadsheet to help me work out the translation:

In the end, I think it came together very well. Madison loves it and keeps it on her desk.  I had a blast, learned a lot along the way, and stretched myself more than a little. I lost count early on of how many hours I put into this but it's been like many other projects over the years - some little nugget I learned here is guaranteed to help in another project later on.