These "cracked" eggshells get their jagged edges from electrical tape: Use a craft knife to cut a random zigzag pattern into a strip of tape, and position it around an egg that has been dyed a pale color. Dip the egg partially into the same dye bath again, up to the tape, holding it in until the desired darker shade is reached.
A chirping chick is made by dabbing food coloring into vinyl stencils.

These are so cute! Can't wait to make them for Easter next year!