The paper cone is widely used in decorative work. It is inexpensive, easy to make, and can simply be discarded after use. It is especially valuable if you are working with different colors; simply make a separate cone for each color icing.
Although it is possible to fit metal decorating tubes inside paper cones, the cones are usually used without metal tubes for writing inscriptions and for making line drawings and patterns. In other words, they are used the same way you would use a pastry bag fitted with a small plain tube. Because paper cones can be made rather small and are easy to control, pastry chefs generally prefer them to pastry bags when they are doing delicate work. For the most delicate work, a special type of plastic or cellophane is available that makes finer lines than paper because a smaller, cleaner opening can be cut on the tip.