Simple replacement actuator for Sanwa-clones (Mr.Joystick etc.). Shortens the throw of the stick a bit and pushes spring more to give a bit tighter stick. Just remove the lock collar, pull old actuator out and replace in reverse order.
Only tested with Mr.Joystick arcade stick, your mileage may vary with other arcade sticks.
Recommended is to print with 3 outlines, giving almost 100% fill.