Magnetic Micro-Machines (MMM) have been proposed as effective tools for minimally invasive surgery. We propose an innovative and low cost MMM manufacturing process based on casting of a mixture of SmCo powders and acrylic resin into silicone moulds. After developing a MMM prototype, we tested its swimming ability by using different siliconic oils of known kinematic viscosity. The propulsion efficiency, given by the velocity and frequency ratio, has been found comparable with other MMM reported in the literature.