Yeah, those rubber bands would certainly work.
Alternatively, if anyone's dead-set on a case instead, then the Sony Xperia Z1 handset is too large but the Samsung GS2 is quoted as:
125.3 x 66.1 x 8.5 mm
From the Photoshopped pic I posted a few days ago, we can see that the NW-ZX1 is quite a similar size (thickness notwithstanding):
So something like this could be modified, if you're handy with a Stanley knife, but notice that mostly the buttons would already be free even without modification (you would have to slide the NW-ZX1 into the case, back-to-front, though - i.e. with the screen facing away from you):
OR, a vertical-style case... (again, I'm proposing that this be slightly modified with a Stanley knife, to make access to the NW-ZX1 buttons)
It'd be nice to find one that doesn't hinder the screen at all, but then you need one that clips directly to the DAP, and that's very unlikely to fit accurately if it's designed for a smartphone, especially considering the unorthodox bump on the rear of the NW-ZX1. On the plus side, given that the NW-ZX1 is 6mm narrower than the GS2, this can provide a little room for the additional thickness of the NW-ZX1.
I reckon something like the cases above, with clearance made for the NW-ZX1s hardware buttons, would therefore be a quite satisfactory compromise, and I'm sure others will find even more suitable cases, in due course.
It certainly beats shelling-out a couple of hundred bucks for a leather case that doesn't allow any access to the DAP whatosever!
Edited by Mython - 12/6/13 at 1:42pm