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.
That wire could use a better insulator.
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.
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.