My latest batch of K3s just arrived hours ago, and it has many fewer working eink screens than the previous batch.
To get an 8x8 grid, I will have to mix screens between models.
Surprisingly, I discovered that the K3 and K5 use the same eink connector, so at some point I need to try a K5 screen in a K3 (or vice versa).
I certainly plan to make it look better than these eink walls:
http://www.wired.com/gadgetlab/2008/11/a-full-wall-of/