-Minor differences in physical properties are responsible for making a combination desirable, but these differences are also responsible for making the combination incompatible
-For this process, polymers must have similar melt viscosities to sustain a laminar flow. All the viscosity differences may be more or less tolerable, according to the material location inside the composite structure along with the layer's thinness
-Requires more sophisticated extruder and its operator. This implies extra maintenance cost of the equipment.
-Demands considerable planning as well as forethought in the system design