Catan Magnetic Bases - 3mm Spherical Neodymium

A remix of http://www.thingiverse.com/thing:242898 designed to work with JAWong's amazing Catan tiles http://www.thingiverse.com/thing:26979
I've also designed some seaside tiles with matching bases http://www.thingiverse.com/thing:1108755

I couldn't find any cylindrical magnets polarised correctly.
Spherical magnets are cheap, easily available and are able to rotate achieving the same effect.
One a side will work, they're not particularly strong so I used two a side.