HandTracker is an open-source 3D mouse designed for use in CAD software and games. It has 6 degrees of freedom. It functions like a regular mouse when flat on the table, but when you lift and rotate its top shell you can e.g. control the orientation of 3D objects or viewpoints. It is built around the RP2040 MCU, an optical tracking sensor and an Inertial Measurement Unit (IMU).

Here it is being used to control X-plane:

Some close-ups of the hardware, also see the OnShape CAD files: