Here is a manual of how to make a heart shaped egg.
Step 1: Cut milk carton and fold it in half lengthwise.
Step 2: Make a hard boiled egg.
Step 3: While the egg is still warm, peel the egg and put the egg on the milk carton, place a chopstick on the center of the egg, and put rubber bands on the both ends.
Step 4: Leave it for about 10 minutes. (Keep the egg in the fridge if it’s summer time.)
Step 5: Take the chopstick off and cut the egg in half.
Source: annathered