What can you use to write on a fiberglass cast with?

You can use a variety of writing instruments to write on a fiberglass cast, including permanent markers, gel pens, or fine-tipped Sharpies. These options are ideal because they dry quickly and adhere well to the cast's surface. However, it’s best to avoid using regular ballpoint pens or pencils, as they may not leave a clear mark. Always ensure that the ink is non-toxic, especially if the cast is on a child's limb.