I'm appreciative of all who have replied to this. But my
progress is pretty slow.

I suppose one of the reasons everything goes so slow is:
I have one set of flat packs and any misstep just about
kills the project and whatever investment in materials
and tools.

One handy part of having a 3" hole cutter is it can be
used for the front (speaker cutout) and the back (terminal
cups are 3" too.) And so it goes. I should be rabetting
the baffles for flush mount as well. It is considered a
requirement of the design. And not much play for screw
mounting those little 3" Tangbands. I am doing a practice
mount for all these things: an open baffle that can also be used
for break-in using the technique of running white noise
through the speaks at high volume in a sealed and damped
container.