This what I think will be the final core board configuration. 

All of the functionality is tested, except I haven't physically made a core stack yet. I'm happy with the ambient light sensor and hall sensor "buttons" hiding under M - + S. The layer select function works well too, composed of solder jumpers and the two big chips in the top of this photo:

I'm also quite happy with the weaving in this one. This is my best one yet thanks to a 3D-printed assembly fixture. The fixture helps guide the sense wire crisply. My vision of making the cores easier to thread by placing the fixture on from both sides of the PCB has not yet been realized, but manually weaving plane isn't too bad... after some practice on the first two.

In the last project update I thought I could get to the point I have 8 of these stacked by now, but other priorities called. I will get these stacked after I complete the Logic Board layout. I'm reviewing the schematic now and wrestling with which features to drop from an over-crowded board. This board WILL have the ability to drive all 8 layers of core planes, and that is going to be fun when I get all the core planes visualized in real-time on an LCD!