There are two common ways to make a hollow egg or rabbit:
- If you are using a mold that is open at one end - Fill a mold full of melted chocolate, let it sit for a moment or two and then pour the liquid chocolate out. Some of the chocolate will have solidified on the inside of the mold. This is also a common technique for making filled chocolates (for example, chocolate covered cherries or cremes). It works well if there can be a hole in the figure (usually on the bottom) when you get done.
- If you are using a complete mold - Open the mold, fill it with some melted chocolate, close the mold and turn it so that the liquid chocolate coats the entire inside of the mold. Then open the mold after the chocolate has solidified.
Here are some interesting links:
Cooking Crabs