You can make straight hair wavy a number of ways. You can use soft or hard rollers, on damp hair and let dry. Usually a larger size creates wave instead of curl. You can also purchase styling products that let you ‘scrunch’ your hair into waves. And you can purchase a big curling iron that will let you create waves as well. It all depends on how much time you have to do your hair, and how much money you’re wanting to invest in it.