Why not a mirror under the cutlery. Attach the knifes to the glass via powerful magnets under the mirror or sticky tabs of Velcro on mirror surface and mate to sticky tabs of Velcro on the knives. Worst outcome is you see yourself every time you look into the display! However, the mirror gives you more of the knives to view.
How about an illuminated background of opaque glass/plastic/plexiglass with flat led strips under the light transmitting surface. You could see the knives even in poor light or total darkness. Perhaps take a block of something interesting like colored glass/lively-grained wood and have the negative surface of each knife milled into the glass for a perfect fit, with a backlite or not.
Animal skin. Leopard, for example.
Camo, something modern.
A giant photo of you, your family, your favorite place, the Buck Factory or something else blown up to fit the interior.
Chainmail.
Cement.
Corian, lapis lazuli blue cut to fit. Maybe mill the surface in some manner, spell out the word BUCK for example.
Build the display around flatscreen and roll pics of cutlery on a loop slide show. You could show about any images or video behind the knives so it would never get to be old news.
Marble. Find a pattern you like and have the countertop craftsman cut and finish to your desire.
Granite. Find a pattern you like.
