STL files for the components and code for the drivers are posted on GitHub. The magnetometer used to sense 3D position with respect to a fixed magnet is the Adafruit TLV493D Triple-Axis Magnetometer, which sells for US$ 5.95 in quantity 1–9. The microcontroller is a Raspberry Pi RP2040.
This is a 3D viewpoint controller, which implements the functions usually done by combinations of 2D mouse movement and keyboard button presses. It is not a complete six degrees of freedom controller, which, by analogy to a mouse, might be called a “bat”.