Material extrusion (MEX) is a type of AM technique in which filaments or pellets are melted enough to be extruded to make parts. Other names of the technique are fused deposition modeling, fused filament fabrication, fused pellet modeling, etc. The technique requires the feedstock in the form of filaments or pellets to be converted into materials that must have extrudability. The conversion of the feedstock in the form of an extrudable material is part of the technique. This technique is not applicable to those techniques that rely on material extrusion to make parts without prior conversion. For example, if there is a feedstock in the form of extrudable slurry, paste, gel, or bioink, material extrusion to make a part will not come under material extrusion (MEX). Though, it is technically material extrusion. Extrusion of an extrudable ink comes under ink jet printing, ink writing, extrusion printing, extrusion-based 3D printing, etc. These extrusion-based 3D printing do not include MEX.