I like to use handmade paper cones if I need only a small amount of a mixture such as chocolate, royal icing or buttercream for decorating. They are quick to make and have the added advantage of being disposable. You may snip the tip of the cone off with scissors, but I find I have better results if I try to roll the tip to the size opening I need. Sometimes the cut surfaces of the opening will make squiggly rather than straight, even lines when you pipe. To make a paper cone (see illustration):