I have a Momo Cobra knob with an aluminum 6 finger sleeve/timing pin (custom CNC machined at the Aerospace Co where I work. TRUE aerospace CAD designed/machined
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Actually had the shifter rod (E46) and knob internal CMMed to generate the solid model/surface data. I then generated the part program data for the 5 axis Micron CNC milling machine and lathe (6061 T6 alum alloy).
It took around 6 hrs to CMM parts, produce solid model/part programs, machine parts, deburr, assemble and install in knob. It took around 6 hrs.
In the pics you can see the 6 fingers that locate in the BMW OE shaft groove and the timing pin that slips into the shift rod top slot. This is now a direct/tight snap on knob for BMW application.
This knob is 3" tall and hella weighted, 11oz. Will sell for knob cost, $100. (the 6 hrs of shop time/materal to produce the sleeve is free!!!)