Part Orientation
Whether plastic or composite, FFF or CFF, 3D printed parts are strongest in planes parallel to the print bed — so the print orientation can literally make or break a part. Deposition-based 3D printers build parts in layers of plastic laid down on top of one another. Almost always, the molecular bonds forming the material extrusion itself are stronger than the adhesive bonds of one extrusion of plastic laid on another. Think of the layers like cracks or wood grain - they are slices of material stacked together, so it’s easy to pull those slices apart vertically, or push them past each other in shear.