Excerpt from the book "Magnetic Current" By ED Leedskalnin When you were making the small magnets with a single copper wire you wasted too many North and South Pole individual magnets. You only got in the steel wire very small part of the magnets that came out of the copper wire. You are still wasting the North and South Pole magnets. You do not get one half of the magnets in the steel or iron bar from those which are in the coil. To get more magnets out of a coil put the coil in steel or iron tube, then the tube outside the coil will be a magnet the same as the coil's core, but the magnet poles will be opposite. it means at the same coil end if the core end is North Pole the tube end will be South Pole. In this way you will get almost again as much magnet out of the coil and in the core and tube.