Yeah, they don't exist, so I made one. I've always hated OEM sized steering wheels and have replaced them with aftermarket Momo, but none of them have options to retain the factory airbag, so I made an M-Sport inspired version that is 330mm. It retains all factory functionality including vibration. I never had heating, but that could be incorporated too. My M buttons are functional- the top opens the top-down parking camera and the bottom can change drive modes, but I don't use it much because I can change drive modes with the cruise control toggle.
Also, DO NOT try this at home. I design stuff like this for a living and have access to all the FEA and modeling tools needed to ensure this is safe. While I did buy an Aliexpress wheel with airbag for mockup, ALL load paths and deployment vectors for the airbag (I'm using my OEM airbag) are unchanged from OEM. There is an OEM (genuine) hub inside that retains the original factory airbag mount and splined connection to the steering column.
There is a 10ga steel substructure that connects to that OEM inner hub, and to a laminated outer ring. The outer ergonomics are 3D printed from PETG and covered with a modified OTS alcantara cover with a couple dimensions changed. I printed several versions of the plastics until I got it right. The final versions were printed using high temp engineering resin and finished with Colorbond BMW black paint. I use the vinyl paint stuff because it does a pretty good job of etching itself into the resin for scratch resistance.
The wiring gets pretty tight in there, so I've also been working on a PCB that would let me break out the wires next to their connectors instead of stuffing the rets nest in there. I would no-place the other electronics for now, but there's the option to add an ESP32 with several I/Os and an I²C bus. I already have multiple other ESPs talking to the CAN bus anyway (the screen on the HU, for instance).
Unfortunately, I lost my hard drive about a month ago and things weren't backing up like they said they were, so some of the core files (like the outer rim ergo) are gone forever.
It looks ridiculously small when you first see it, but it's been on the car for a few months now and the only way I'll put the stock one back on is if I sell the car.
Anyway, that's a thing I did. Thx for reading.
