How to build one of these electro magnets?

Ive seen plans to build electro magnets where a metallic object is dangled upside down. this company inverts it so the metallic object is propelled upwards. from some of the pictures ive found it looks to be four magnets working together. any one have any info on building one from scratch? the first site below have videos of it in action.

http://www.floating-lamps.com/floating-technology/
www.crealev.com

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