The Pimple Stick. When i started making Knock downs in 1989, I called them pimple sticks. This pimple stick is 4 inches long without the tip. It does, however come with a Dentcraft BP-3 tip! The Pimple Stick is made from Carbon fiber tube with a diameter of 1/2 inch. It features flats for easy and secure, comfortable gripping. The striking head is made from a hard plastic that is replaceable and interchangeable with a steel one if you wish.