The closer way I've found is this guy making it with a recycled transformer, a hard drive magnet, a jar lid, some wood, and some cables.
https://www.youtube.com/watch?v=cEMXlLqwwTA (First part. 7:07 min.)
https://www.youtube.com/watch?v=MXpprO5h79I (Second part. 9:32 min.)
Those videos are in Spanish but subtitles are available.