In case others are wanting more information before chiming in:
I think aluminum might be best, because then I won't have to worry about a finish. Anodized would be even cooler. I'm guessing it'll be five pieces:
- cp box : I want the corners pretty round.
- cp top : I want no edges/corner on this, either, but that could be difficult with the box corners being round.
- cp bottom.
- yoke housing: one piece, that is bent into form.
- yoke mounting plate.
Six holes, total: four buttons, spinner shaft hole, joystick hole.
Except for the bottom, thickness should be enough so that it doesn't flex. I'm thinking the pieces could attach by studs and nuts, via flanges, though I might consider welding of the majority of them. The former would mean it could be shipped mostly flat, though that may not matter.