A second component of the clutch (part B) is a small disk attached to the motor shaft. The disk has 4 holes threaded M3, which match respective 4 holes (dia 3mm) in part A. 4 set short nylon M3 screws are threaded into the holes in part B.

A second piece of the 20 x 3mm aluminum bar is attached to the Robofocus motor (this is bracket part 2).

Also shown is M5 thumbscrew used to screw the two parts of the bracket together.