The Magnaprobe Mark II uses a gimbal mounted magnet that traces out the shape of magnetic fields in 3D around bar magnets; only $9.95.
It is a simple but elegant tool for showing the three dimensional nature of magnetic fields. It consists of a small alnico bar magnet that can rotate freely on 3 axes (i.e. behaves like a gyroscope) and will map out x, y and z coordinates as you move it around a magnetic source.
In the image you can see we have mounted a small bar magnet underneath a translucent FieldView™ viewing table. This allows you to also sprinkle iron filings on the viewing area for comparison to the Magnaprobe if you are interested and also allows you to sweep the Magnaprobe below the magnet. The Mark 2 Magnaprobe can be used to determine the magnetic orientation of any our Permanent Magnets.
See the Youtube video of the magnaprobe in action with bar magnets.
Note: Avoid contacting other magnets. If you do so by accident, detach the Magnaprobe by holding its magnet. Do not simply pull back with the handle as you will ruin the device.