I picked the grill material at the Homedepot, it's radiator screen material made of aluminum. Very easily cut and bent, it slides into the little slot between the main cabinet and the fascia. I went this route because I did not want any grill cover holes on the face of the speaker but still wanted to protect the drivers, mainly the very expensive 9500 tweeter.
I remember reading at the Madisound forum that the NorthCreek tweeter and the 9500 sound very similar. I'm sure George has built a great tweeter. I may build a full set of these little guys for my HT setup, that's how mush I love the natural sound they reproduce. George has told me that he is working on a horizontal MTM center channel for the Okara (Ikemo), great for HT! I just received the amps and drivers for the Poseidon subs, can't wait to get started