Zhixalom's Arcade Joystick v2.0
To get a smooth surface I sand them with gradually finer grain sandpaper. Starting with P40, then P60, P100, P120, P150, P180, P240, and finally P320.
The first rougher standings seems to be the most important, hence the smaller steps in grain.
This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/lNWZlFKHzlL