Well a piston may be a good idea , and i can put a wood between the piston and the base magnet , so when i turn it off they won't stuck ! , yeah it may be rectangular , thanks ma.
i thing your guess was right , i needed to use the magnetis once as a usal metal and once as magnet , so to of them can get attracted to each other , again my setup : i have an Cylinder , on the top there is a magnet , and in the Cylinder there is a free magnet + water, by turning ON the up...
thanks for replying first of all , well , i have to magnets , and between them i have water , when i turn on the magnet the attract to each other and push the water , after that i have to release them ,and get back to the first position , so i need to control them , i heard of something called...