A - Materials: The use of technical materials to satisfy transpiration or thermal request needs the supply of many king of different materials.
B - Stitching: Technical materials could need particular stitching technique different to the standard way for the leather. A system that offers many kind of materials needs a flexible stitching station able to adapt to each typology.
C - Outsole and Insole Production. If the system have the capability to satisfy shock absorption customization the production of the sole needs more complex and correct technique able to realize a various set of shock absorption.
See also:
Complexity, Capability to satisfy functional request, Assembly, How the capability to satisfy fitting impacts on assembly, How the capability to satisfy aesthetics customization impacts on assembly.