How was Gluttony made in Fullmetal Alchemist?

In the anime/manga series Fullmetal Alchemist, Envy was made when Father attempted to create a homunculus that would encompass all seven deadly sins. However, the result of this experiment was the "failed one," Envy, who only inherited the sin of envy. Gluttony was created separately, from Father attaching a fragment of the True Philosopher's Stone to the original Gluttony.