In a nutshell, this would be a 'free energy' machine which violates the Law of Conservation of Energy. In layman's terms this means that that you can't get more work (energy) out than you put in which would be required for such a machine to work. There's only a certain amount of work a closed system can do before it needs replenishing with energy...the driving energy is lost through heat and friction.
To give you an idea of how inviolable this law is considered to be you have give the US Patent office a WORKING model before they will even consider giving you a patent...for other types of inventions they only need to be outlined on paper and presented. If you did have a working continuously self-powered magnet model you would surely get the Nobel Prize and be as famous as Einstein and Newton! . I hope that drives the point home. ;D