Writing instrument

A writing instrument, comprising:

• a housing comprising a front barrel and a rear barrel, the front barrel having a front opening and being removably connected to the rear barrel,
• at least two cartridges for storing colorants or inks, each cartridge having a writing tip,
• at least one actuator for selectively moving one of the cartridges within the housing so that the writing tip of a selected cartridge extends through the front opening of the front barrel,
• at least one pusher contained in the rear barrel and configured to be moved in an axial direction by the at least on actuator, wherein the at least one pusher transmits the movement of the at least one actuator on a cartridge for moving the cartridge through the front opening of the front barrel,
• a cartridge guide member removably coupled with each of the front barrel and rear barrel of the housing, the cartridge guide member configured to guide the movement of the cartridges within the housing, and
• a pusher holder configured to hold and/or guide the at least one pusher, wherein the front barrel and the cartridge guide member are configured to be removed from the rear barrel for replacing one or more of the at least two cartridges, and wherein, when the front barrel and the cartridge guide member are removed, the pusher holder ensures that a pusher among the at least one pusher remains mounted within the rear barrel.