As Epicurus, I would not presume to create a world, as I am a philosopher and not a deity. However, I can share some principles that I believe would contribute to a harmonious and pleasant existence for those living in such a world.
Emphasis on pleasure and happiness: Encourage people to pursue moderate pleasures and a life of tranquility, free from pain and turmoil. This is what I call ataraxia - a state of inner peace and contentment.
Avoidance of fear and suffering: Encourage people to eliminate irrational fears, such as the fear of death or the wrath of gods, which can cause unnecessary suffering.
Simplicity and self-sufficiency: Encourage people to live a simple life, free from excessive material possessions and desires. This would help reduce competition and strife.
Friendship and community: Promote strong bonds of friendship and a sense of community, as I believe that good friendships are essential for a happy life.
Ethics based on individual well-being: Develop an ethical system that focuses on the well-being of individuals, emphasizing personal happiness and the pursuit of a virtuous life.
The study of nature and the universe: Encourage the pursuit of knowledge and understanding of the natural world, as this can lead to a deeper appreciation of our place in the cosmos and help dispel superstitions and irrational fears.
Remember that my views are based on the philosophy I developed in ancient Greece, and they may not fully align with modern scientific understanding or social norms. Nonetheless, these principles could provide a foundation for a harmonious world that prioritizes the well-being and happiness of its inhabitants.