Systems, devices, and methods according to the present disclosure are configured for use in additive manufacturing. Systems for additive manufacturing can include stand-alone manufacturing units, a series of units on an assembly line, or a high-capacity system with workflow automation features including a conveyor for transporting parts to or from a build area, or a robotic arm for transporting parts or adjusting a system component. An additive manufacturing system (100) can include a flow regulator (130) to change a temperature of a thermoplastic material at or in a tip (150) of a material extrusion nozzle cartridge (171), such as to enable or inhibit flow of the thermoplastic material from the tip. The flow regulator can be configured to provide a specified gas or liquid at a specified temperature, velocity, or volume.