Of course you’ve got to CNC the parts before anything else!
Keep in mind the Aluminum goes on the machine twice, once for the fold grooves, and once for everything else. And he walnut goes on the machine three times. Once for the front holes and the rounding of the top and bottom. And another two times for each side, drilling the screw holes.
You might be able to get away without tapping the holes in the aluminum, but using a tap to make the thread is a good idea. I suggest #6-32, as that’s what I designed for. And the screws are #6-32 × 1/4" set screws.
Start with only a couple screws in the aluminum, so you can still see the holes in the walnut. Line it up the walnut, and turn the screws in. Once you’ve got a couple screws done, you can now get the rest of them in.