UPDATE: Remixed for dual magnets per side, here http://www.thingiverse.com/thing:2093075
I had 3 mm x 1 mm cylindrical magnets sitting around. These did not fit into Dakanzla's bases particularly well (and it required many magnets). I've modified all the terrain tiles to have 3 mm slots in the sides of the bases to allow magnet-to-magnet contact, which makes the interaction stronger. The only catch with this is that you have to get the polarization right for the bases. Basically, just alternate polarization as you go around the base. Will add a video shortly to show how I do this and makes it very quick.
Note: The only tiles where you start with the polarization matters are the ports. 6 ports need to have consistent polarization with the "port face", and 3 ports need to have the "port face" have opposite polarization.