attaching the case sides

As I mentioned, the other sides of the frame did not need to be shaved, they were adequately flat as it was.  So, my overall concept of relying on the pre-cut lumber faces, seems to be partially vindicated: it just didn't work with a particularly long, and particularly warped, piece -- which I probably should have rejected at the start, but one of my aims here is to learn how to make all this work with less-than-perfect materials, so there ya go.  Use cheap lumber, spend five days sawing.

Anyway, the other sides didn't need all that.  Just needed to trim the plywood on the top and bottom, as I'm doing here:

I affixed temporary wood "step sides" to hold the first side in place, at the right level.

A little Duck Tape on the bottom seam lets me do the gluing right here, in the living room.

My lovely new clamps in action.  I was planning to use thicker lumber for the clamp arms, but actually the 1x3s I ended up using turn out to be a good choice, because when they are under operating pressure they bend just slightly, allowing me to judge the distribution of the force better.

I'm doing the long sides first.  Then, I will have to carefully fit the smaller pieces to connect up the segments, hopefully ending up with joints that look nice.  There has been significant "creep" in terms of my aesthetic aims for this project.  At first, I was planning to expend exactly zero effort on making it look nice, as a proof of my theorem that only certain aspects actually matter to the tone quality.  All cuts would have been right-angle, with the resulting gappy joints just being a part of the look.  But, I didn't have the guts to hold out with that attitude!  As this will be an instrument which I will use and live with for years, assuming all goes well, I can't help myself from making some concessions (i.e., extra effort) towards aesthetics.  Again, as part of the aim is to develop a general plan which others can replicate, I assume the desire to have something which looks nice would be important to most of us, and so the effort may as well be counted as "necessary".  If the instrument is so ugly that nobody will let it into the house, then it's not a very practical solution for the working musician!