I made this today - in the basement, as it's far too humid to work outside.
I started with a 2" trailer ball; old, rusty and beat up. Cut off the flange and nut, then chucked it in the lathe. Using files, I cleaned up the outside. Then, I drilled, bored and tapped the hole in the end. That got me to the stage shown in the first pic.
Next, I made the aluminum mandrel, and mounted the ball on that. Using a carbide bit, I slowly took off the neck and rounded it to match. I made an adapter (polypro) to match the shifter in the car. Then I sanded. And sanded. And sanded some more. Finally, a bit of a polish on the buffing wheel. Hard to tell, but it's nearly a mirror finish.



Weighs in at 15.6 oz with the adapter. I'm going to give it a go this evening, and see how I like it.