Is pencil a common or proper noun?

The noun pencil is a commonnoun, a Word for any pencil of any kind.

A proper noun is the name of a person, place, thing, or a title; for example:

• Mr. Pencil, Leapfrog Explorer Learning Game
• Pencil Bluff, AR 71965
• Pencil Street, Shelbyville, TN
• "Steal a Pencil for Me", 2007 feature length documentary film