Abstract: Various writing instrument parts are assembled to an insert that is inserted into a hollow body of the writing instrument to complete the assembly of parts. The insert has a glide stop and a spaced cartridge guide, and a compression spring pushes against the cartridge guide and a glide removably secured to the inner end of the cartridge. A clip is hinged to the insert by a snap-on socket fitting over a hinge bar. A biasing spring fits within a clip pocket and an insert pocket to prevent unseating the snap-on hinge. The clip pocket is formed by inwardly extending walls that telescope with the insert pocket to prevent twisting off the clip. The insert is held in the hollow body by a locking projection that fits within a hole in the wall of the hollow body member.