A really nice wooden case would be awesome.
I could certainly make one myself but it would take many hours that I don't have.
So, what chassis would you build it around?
The only keyboard that I personally own, that is really rare and special enough to warrant that kind of investment of time and energy (ie money), is my Model F 122-key terminal keyboard. And how many of those could somebody sell?
My guess is that the VERY most serious key-pounders use Filcos, but even those divide between full-size (yeah!) and 10-key-less (boo) varietals. (boob-lovers are off my radar screen)
But back to your point: a really nicely finished wooden case would be totally awesome.
And in my opinion, the ultimate "finishing touch" would be BRASS keys !
If I rained on your parade, I am sorry.