Large‐scale sub‐20 nm regular pattern obtained by self‐assembly of di‐block copolymers. The combination of reference free grazing incidence X‐ray fluorescence (GIXRF) and GIXAS techniques enables a complete characterization of such a 3D system and provides a potential calibration sample for 3D analytical techniques. This is reported by Masoud Dialameh and co‐workers in article 1700866.