3D micro-extrusion of metals is a 3D printing technology that turns a digital model into a 3D part by the controlled extrusion of a powder loaded paste. The rheological behavior of the paste which consists of metal powder water or solvent and binders is a major factor determining the printing performance in terms of part quality resolution and productivity. After printing a thermal treatment is required to remove the binder and sinter the powder particles similar to conventional powder metallurgical processes. Metals that have been successfully processed include titanium stainless steel and copper alloys. The large freedom in design of this 3D printing technology will be presented. Monitoring the printing process by integration of dedicated sensors that allow the detection of the extruded filament dimensions is performed in view of quality control.