The overall assembly is going well.

I have all eight Tile Holder Buttons put together and tested, and I have four of them installed onto the base. While building the Tile Holder Buttons I  found one hall effect sensor that was either bad, or that I screwed up when soldering (probably the latter), and and couple of other soldering issues (the button wiring is pretty tight in my defense and my eyes aren't what they used to be). Really glad I was testing each one when they were finished.

I was also able to run a successful integration test against what is currently done.  The MacroPad sketch runs as expected but will need some tweaks as the sensors were wired in a different order than the other project to make the wiring neater.