After finishing off the mockup, the only thing left to do was start cutting wood on the project neck.
I had previously thinned the blank down to about 7/8" a few months ago. I thinned it out a little more to about 0.8" as the final thickness, and got to work laying things out.
As I was laying out the lines for the CF bars and truss rod, I noticed that the blank had warped just a few mm, with the headstock end lifting up off the work surface. DOH! I'm not sure what to do with this, or if it will have a significant impact on the final product, but I decided to push forward anyway. I clamped the neck flat to my work table and hoped for the best that the CF bars would help straighten it out enough to continue working with it. I'm just gonna go for it and see what happens... Next time I will install the CF stiffening bars as early in the process as possible.
CF and truss rod slots routed, and CF bars epoxied into place. I left it clamped to the table overnight to allow the epoxy to cure, hoping the added stiffness of the bars will take out the warpage in the blank.
You can see a few of the old lathe-and-plaster nail holes exposed from the 100 y/o 2x4 that I'm using for this build. I filled these wherever I could with epoxy, and one toothpick for good measure

. After the epoxy was cured, I ran the whole thing through a very light pass on the planer one more time to clean up the surface.
Next I got to work on the headstock outline. I used the neck template to give me a starting point at the nut and to cut the main outline of the headstock, then lined up my homemade headstock templates and cut the final shape and stepped relief cuts. After the outline and relief were cut, I took the headstock down to the approx. final thickness with a spoilboard bit. I set up two 1" aluminum L-angles on either side of the neck for a parallel surface for the router to ride on, which worked pretty well.
Unfortunately, it looks like I didn't consider the depth of the TR slot relative to the finished thickness of the headstock, and cut it through all the way to the end of the tapered headstock transition. This might look a bit unsightly at the end of the day. Oh well.
Also, the CF bars seem to have straightened out the playing area of the neck from the previous warpage, but the tip of the headstock is still lifting off the work surface about 2 mm. It's minor enough that I think I can work with it, however... since the neck was clamped flat while routing the TR slot, I didn't account for the warp in the depth of the slot. The TR sits perfectly at the heel end, but is about 1 mm proud of the surface at the nut end. I'll need to deepen the slot to compensate, which might be tricky now that I don't have any straight lines to work off of at the nut.
And of course the tuners I ordered needed a 10 mm drill bit.... 3/8" wouldn't do it. Amazon to the rescue...

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I am also playing around with darkening the wood using a solution of steel wool soaked in vinegar (creating iron acetate IIRC). This reacts with the tanins in the wood, darkening it quite a bit. It didn't do much on pine test piece, but makes a pretty significant reaction on the Douglas Fir, as you can see below on the back of the headstock, and above on the headstock relief cut area. I haven't applied any stain here, just the steel wool and vinegar solution. You don't really have any control over what the final colour is going to be, but the colour change doesn't penetrate very deeply into the wood so it's fairly easy to sand out if it doesn't turn out as expected. Here you can see that it is reacting more strongly with the center strip of the neck blank VS the outer sides. Another application might even that out a little bit, but I'll worry about that later.