For insulating a current you can use plastic/rubber.
insulation materials
Dielectric meterials are good insulator materials
A sharpener is not an insulator. Insulators are materials that do not easily allow the flow of electricity through them, while a sharpener is typically made of materials like metal or plastic which are conductive materials.
Insulator materials will not carry or conduct electricity.
A wooden handle is an insulator because it does not conduct electricity well. Wood is made up of non-metal materials that do not have free electrons to carry electric current. This makes wooden handles safe to use with electrical appliances.
That wire could use a better insulator.
Pure water is an insulator, but in the "real world", water usually has impurities - notably ions - that actually make it a good conductor. This is theory; I don't think it is practical to use water as an insulator.
Plastic, rubber, ceramic, glass.
A plastic bowl is an insulator.
Insulator
It will depend on the specific book and what materials have been used to create it. In most cases, a standard bound book of paper and standard cover will be an Insulator. With specific inks or metallic materials it could be a conductor.
A piece of string is a poor conductor of electricity due to its non-metallic composition. However, it is not a good insulator either, as it can still conduct static electricity and heat to some extent. If you need an insulator, it is better to use materials like rubber or plastic.