Using the power of Earth's magnetism and having the gall to call it a do-it-yourself project... SMH

How strong? Say more please.

Some of the coolest things to have around Where did you get them? I've looked but haven't found any in retail stores.

If you drop magnets in epoxy you will find out where north and south is. That was my surprise when I was trying to glue them with a specific polarity facing up and they started turning.