Technique: How to Prepare your egg shells.
You can empty the contents of a raw egg without damaging the shell. (If you prefer, use wooden eggs, available at crafts stores.) Carefully twist the point of a utility knife against each end of the egg to create two small holes. Insert a long pin through a hole to pierce the yolk. Blow out the insides with an egg blower, available at crafts stores, or with a rubber ear-and-nose syringe. Let drain; rinse. Blow out again, rinse again, and let dry.