Rostock reused effector and carriage magnetic solution

This is a magnetic effector and carriage solution where you will reuse your effector, carriages and rods. You only need to print some small holders for the magnets and steel balls.

I found some good solutions here on Thingiverse but none that's reusing the original Rostock effector, rods and carriages.
That's why I made these things.

magnet_holder.stl is for 12mm diam magnets like these:
http://www.ebay.com/itm/161715991828

magnet_holder_15.stl is for the bigger and maybe stronger 15m