In this thesis, we present an additive fabrication process for arrays of planar sub-µm magnetic elements and investigate the properties of the resulting building blocks and arrays. In this fabrication process, electron-beam lithography technique is combined with ion-implantation, yielding interacting single-domain ferromagnetic elements with minimal surface roughness, embedded within a medium. The implanted elements exhibit intrinsic compositional and magnetic inhomogeneities, enabling temperature-dependent tunability of their magnetic thickness. The magnetic ordering emerged in these arrays is investigated in two different configurations: a quasi-infinite mesoscopic magnetic chain and a square artificial spin ice lattice. In the quasi-infinite mesoscopic magnetic chain, the magnetic ordering is tailored by modulating the long-range interactions through geometrical modifications to the lattice, whereas in square artificial spin ice lattice, the magnetic ordering is designed by leveraging the fabrication method itself. The findings of this study demonstrate the feasibility of controlling magnetic properties at the mesoscale for implanted lattices, expanding the design possibilities for magnetic metamaterials.