I was tired of the stopper always sitting in the bottom of my sink. So I cam up with this design to have it stick to the side of the sink. I used 10 Neodymium Disc Magnets. 5 on each side. It works great.

http://www.ebay.com/itm/lot-100-50-12mm-X-3mm-Neodymium-Disc-Strong-Rare-Earth-N52-Small-Fridge-Magnets-/311723176686?var=&hash=item48942632ee:m:mRGMXXNDXSO0UjNjBoETpFQ