A method for producing a film including a non-magnetic matrix and a plurality of three-dimensional magnetic microstructures arranged within the matrix according to a predetermined pattern. The method includes providing a master substrate with a magnetically structured face formed from a plurality of magnetic field micro-sources, having a magnetic field gradient of between 102 and 106 T/m. The method also includes adding magnetic microparticles or nanoparticles to the magnetically structured face of the master substrate, the particles agglomerating into three-dimensional microstructures arranged under an effect of an attractive magnetophoretic force exerted by the magnetic field gradient on the surface of the master substrate. The method further includes depositing, on the magnetically structured face of the master substrate, a matrix made from a non-magnetic material, in such a way as to enclose the arranged microstructures and to form the film and peeling the film from the master substrate.