A collet mechanism that holds a cannula during molding of a syringe includes first and second arms that form an internal cavity. Each arm has a proximal end and a distal end. The first and second arms are in a closed position when the distal ends are moved toward the internal cavity and are in an open position when the distal ends are positioned away from the internal cavity. First and second cannula guides respectively are mounted proximate the distal ends of the first and second arms and extend into the internal cavity. The first and second cannula guides clamp a portion of the cannula to hold the cannula when the first and second arms are in the closed position.