I picked up a bag of 2 dozen smaller plastic eggs. A sharpie marker works well to write the uppercase letter on the top half and the lowercase letter on the bottom half. With 24 eggs you get almost the whole alphabet. You get to choose which 2 letters get left out :)
Since 24 is a lot for a little person to sort through, I split the group in half and gave 12 to Jay and 12 to Kay. After awhile we switched eggs.
(sorry I can't get this photo to turn)
Just put the "bottoms" in one pile and the "tops" in the other pile. The played for a long time on multiple days with this game!