Here's something I put together over the weekend.
It's a test rig for a Magnetic Rotary Sensor chip. I've tried to minimise the metal in the construction so that it does not intefere with the magnetic fields. The magnet height is controlled by screwing the holder onto the bolt. The alignment of the PCB can be adjusted and then locked down to the base.
The main body is wood with plastic toilet fittings to rotate the magnet. Some Sugru holds the magnets in place, forms a knob for rotation and also holds a couple of plastic pieces that support the PCB.
Here's a closeup of the chip with a 0.5mm soldering iron tip to show the scale