The paper satire rod should not be carved, but the tip can be shaped on a fine sandpaper. By attaching a multi-layer sandpaper to a wooden board, you can practically keep this tool with you. If a sandpaper wears out, just tear off the top and you can still sand your paper pencil underneath. The small sponge helps to clean the abrasive dust that has formed.
You can use it to significantly extend the life of your satire rods.