Hi,
I'm at that stage with my build - got to keep the kids / adults fingers out of the drivers. There are lots of examples of grills for X-Statik and other designs in this circle. Here's what I did... and apologies for the rough finish - nothing is rubbed down or finished yet (and I'm a noob woodworker!):
I used 6mm plywood for the grill frame which seems to work well.
Grills fitted to X-statik and sitting in front of X-Voce. the drawings allow for centre positioning of the driver holes - I made the grill driver holes 7" diameter for good clearance. I've yet to round-over the internal angles.

Detail of the 8mm dia. / 3mm thick magnets buried in the various speaker baffles (I used eight per baffle and eight per grill) - make sure to get the polarities right!! I also superglued (CA glue) them into place to stop them dropping out:


Grill stand off and magnets:

more images :


I intend to paint these in black duratex, going for a smooth-ish coating, then fit (probably glue), the speaker fabric. The small magnets are surprising strong and take the weight of the plywood comfortably.
Hope this info helps?
David