The apparatus and methods of the present disclosure relate to devices comprising spinning magnets driven by electric motors for use with printing or coating equipment. These devices and methods are for orienting magnetic or magnetisable pigment particles in an unhardened coating composition on a substrate. Specifically, these devices and methods are for producing optical effect layers. The apparatus comprises a holder, onto which is mounted a motor and a permanent magnet assembly. The motor is configured to spin the permanent magnet assembly. The holder is configured to be removably fixed to a base of a rotating magnetic cylinder (RMC) or a flatbed printing unit.