in metal MEX, the feedstock composing of metal powder and polymeric binders is heated until the filament is softened and can be extruded through a printing nozzle. The printed material is then deposited on the printing bed, which is heated to increase adhesion between the printed parts and the printing bed so that the 3D part is created layerby-layer following the CAD model [131]. This metal MEX process can also fabricate multimaterial 3D parts, when a printer has more than one printing head or feeding system. Depending on the feeding system of the printer, the metal MEX process can be classified into three types, as presented in Figure 3, which are (a) screw-based, (b) plunger-based and (c) filament-based types [132]. After printing, the as-printed parts require to be debound and sintered in a similar manner to those in the MIM processing steps, as prese