I've worked with real egg shells a few times. I enjoy the texture they add to an art work. Awhile back I used the egg shells as leaves for an india ink tree on notecards. I also covered an Altered Book spine with egg shell pieces and painted it a glossy black for an interesting texture on the book's cover design.
This is a one of a kind hand-cut photo mat from 140 lb. watercolor paper. Designed with REAL broken egg shell pieces then painted with watercolors in monochromatic blue hues.
Measures 6 x 4-1/2-inches. 2-1/2 x 3-1/2-inch picture opening. Mod Podge sealed for long term durability.
This is a OOAK mat. I will not make another just like it...though some may be similar in design. For sale in my Etsy shop that offers less expensive arts and crafts:
http://MamasHouse.etsy.com