  X-ray mirror fabrication for astronomy is challenging; this is due to the
Wolter I optical geometry and the tight tolerances on roughness and form error
to enable accurate and efficient X-ray reflection. The performance of an X-ray
mirror, and ultimately that of the telescope, is linked to the processes and
technologies used to create it. The goal of this chapter is to provider the
reader with an overview of the different technologies and processes used to
create the mirrors for X-ray telescopes. The objective is to present this
diverse field in the framework of the manufacturing methodologies (subtractive,
formative, fabricative & additive) and how these methodologies influence the
telescope attributes (angular resolution and effective area). The emphasis is
placed upon processes and technologies employed in recent X-ray space
telescopes and those that are being actively investigated for future missions
such as Athena and concepts such as Lynx. Speculative processes and
technologies relating to Industry 4.0 are introduced to imagine how X-ray
mirror fabrication may develop in the future.
