The serving trays turned out very handsomely, indeed. Hubbest says they look fittin' to be sold from a high-end boutique.
I found I had to size the corks first, to make sure my pattern came out right. Hadn't realized until then that corks come in different lengths. Also found that the back to the shadow box fitted better if I shaved off a lengthwise fraction of each cork. That left a lot of cork detritus and dulled my Ken Kershaw, but the results were worth the effort.
Serendipitously, the pattern I devised left a hole in the center of each diminishing square . . . a hole that perfectly accepted the top of a champagne cork. Makes a nice visual accent.
Thanks again for the tip, Eranice. I've got Christmas covered.