Finally had an opportunity to watch these two videos - good stuff! I have yet to draw a neck profile in Fusion but plan to soon. How much heavier is the D tube than a regular truss rod?

Oh, a good tip for you is to switch from wax paper to parchment paper. Wax paper will stick to glues so I switched to parchment paper about 10 years ago and I'm still using some of the pieces I started with way back then. Yellow glue, if allowed to dry, will just flex right off leaving a clean piece of the parchment paper. If you try to wipe it off while the glue is wet then it's likely that piece of parchment paper will end up in the trash.

I'll check out your full build thread soon - thanks!