A cork borer is a laboratory tool used to bore holes in cork, rubber stoppers, or other soft materials. It consists of a cylindrical metal tube with a sharpened edge at one end and a handle at the other end. To use the cork borer, the user places the sharpened edge on the surface of the material and applies downward pressure while rotating the borer.

The sharp edge cuts through the material, creating a cylindrical hole of a specific size. Cork borers come in a variety of sizes, and the size of the hole is determined by the diameter of the borer.

Cork borers are commonly used in chemistry, biology, and other scientific fields for tasks such as inserting thermometers, creating test-tube stands, or making custom rubber stoppers.