Proper nouns are names of specific people, places, or things. Since "pencil" is a common noun referring to a general type of writing tool, it doesn't have a proper noun equivalent.
However, you might be thinking of a specific brand of pencil, which would have a proper noun, such as:
* Bic
* Ticonderoga
* Staedtler
If you have a particular brand in mind, let me know and I can help you find its proper noun!