Final answer:
In hair design, cylinder rollers are used to create uniform curls within straight shapes, and they must be placed at a 90-degree angle from the scalp.
Step-by-step explanation:
In hair design, when creating uniform curls within straight shapes, a cylinder roller is commonly used. This type of roller, which can also be referred to as a magnetic roller, is designed to create a smooth and uniform curl throughout the entire section of hair. To achieve the desired look, each roller is placed at a 90-degree angle from the scalp, and the hair is rolled evenly and securely. Cylinder rollers come in various sizes, and selecting the appropriate size is essential for achieving the desired curl tightness and shape.