Hello, i need a small electro magnet with it's dimension not bigger than 8 millimetre (0,31 inch) in diameter with a length under 10 millimetre (0,39 inch). I want it to be as powerful as possible, where do i find such magnets? And how should i make my own? How powerful is it possible to make it? Could i just use a big battery and waste much electricity to the small magnet, in order to make it really strong?