(eng): Optimization of ferromagnetic bodies exhibiting fast spatial oscillation of magnetization is investigated especially in cases when these oscillation exhibit a "mesoscopical" pattern uniquely determined by external magnetic field, as in the case of uniaxial magnets. A proper relaxation converts the task to a standard optimal control of a variational inequality, which is used to obtain anapproximate solution of the original problem as well as to propose an effective finite-element numerical procedure.