As humans, we can’t detect magnetic fields, but we take advantage of this phenomenon every day in the form of motors and various sensors. Even electrical wire produces a field when current flows through it. You can sense magnetism with a compass, but if you want to visualize it in three dimensions, maker ‘amamitof7’ has a solution in the form of this Arduino magnetometer.
The device uses a trio of analog Hall effect sensors to measure the strength of the magnetic field. This data is fed to a MKR WiFi 1010 (or Uno), which generates an isometric representation of the field on a small TFT display.
One could see this used in a variety of diagnostic applications, or perhaps as an excellent physics teaching tool.