I suggest First4Magnets: Buy Magnets Online | first4magnets.com
Do the staff have to remove all metal objects before entering the store?
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Some fridge decorations are all ready rubberised and flexible being bonded with the magnetic compound, simply put, a magnetic rubber mat. Cut one of them up with a pair of scissors, not as strong as your other magnets but could well be strong enough to hold two model hoses together.