The DIY screen material may have creases or wrinkles after it has been stored for an extended period of time. These are known as memory lines. This is both a normal and correctable phenomenon. The creases/wrinkles on the DIY material will disappear in most cases if the material is stretched out for about 24-48 hours. After that time has passed, the lines should vanish. To speed up the process of crease/wrinkle removal, you can try applying heat to the material (example: a blow dryer at low heat). If attempting to do this, please move the heat source across the material to avoid having the heat directly on one spot for a long time.