enlarged rostock magnetic_platform

made for my next enlarged rostock
http://www.thingiverse.com/thing:80472

the carriage is here
http://www.thingiverse.com/thing:139264

but with correct mesures (magnet are 13mm X 4.6)

this is the correct magnet (The one i used)
http://www.ebay.it/itm/Super-Magnete-al-Neodimio-CSN-13-POTENZA-3-Kg-FORO-SVASATO-BASE-IN-ACCIAIO-/400535138240?pt=Monete_Italiane_in_Lire&hash=item5d41c12fc0

and these are the balls
http://www.ebay.it/itm/261115915534?ssPageName=STRK:MEWNX:IT&_trksid=