I found out about the BNO085 about an hour ago so I don't have it yet, I will probably begin design work after the new years. I am planning to use the onboard 3DOF magnetometer for translational movements, and the gyro for rotational movements.

For the controller I plan to use the ATmega32U4, as I know it supports spoofing itself as a genuine 3dconnexion device. I have a few pro micros laying around, but they lack a stemma or qwiic port. I would like to make use of the stemma/qwiic connectors on the BNO085 to free up some pins for macro keys, so I might end up buying another board. I also have a qt py rp2040 I can repurpose which does have a stemma qt port, so I might experiment with that as well. My knowledge of microcontrollers (and electronics in general) is extremely limited so if anyone reading has any suggestions that would be greatly appreciated. 

Benbouz's design already incorporates magnets for its 3DOF magnetometer, so I am anticipating I will be building off of his design at first. The only issue I can forsee is that rotational movements will affect the magnetometer readings but that is yet to be determined. 

If you are like me and have been trying to find a good DIY SpaceMouse solution, here is my personal experience with the ones I've built. The design of the Space Mushroom is limited in range of movement, which affects translations and rotations along certain axes. It does seem like the easiest 6DOF solution to source and build however. The Spacefox is nice, but my spring loaded potentiometers have trouble returning the knob to center. It is also a little too tall and the knob a little too large to comfortably incorporate into an enclosure. Other than that, usability is very good. Benbouz's SpaceMouse unfortunately only supports translational movements, but has (in my opinion) a nicer looking design than the other two and a very good feel. 

I was looking at the OS3M as another project to make, or base a design off of utilizing 6 hall effect sensors rather than inductive sensors. This looks like the most compact solution, but requires a custom PCB. The compliant 3d printed spring it uses might be something to look into. This is a project I haven't tried, but is definitely worth looking into if you're looking for an already complete solution.

Thanks for reading!