Though you can use hair extensions, having naturally long hair can save you a lot of time, effort, and money. This costume looks particularly good for those with long hair. However, creating your own costume from scratch is not advisable, since it’s very complicated. Men’s Aquaman Costume · After that, preparing the costume is as easy as finding a red shirt and some worn-out jeans. You only need to purchase a straw hat to complete Luffy’s getup.