This thesis describes the process of redesigning the 3D-paintbrush. It looks into extruder screws for plastics and finds the best design variables for the 3D-paintbrush. Vortex cooling has been used to cool the extruded plastics fast and efficient. With the findings for melting and cooling the thesis looks at human-machine interaction and combines these findings into a final redesign. A mockup is made of the redesign to validate the interaction between the user and the 3D-paintbrush