Put the object ball in the center of the V, use the side notches to help get the ball perfectly centered. Next line up arrow head, to the object ball, to the pocket. Then simply shoot the cue ball so that the center of the cue ball passes directly over the little circle.
Designed for standard 57mm billiard balls.

I printed this in white PLA, then colored the little dot read to make for a better target.

Prints at a single 0.12 layer height. Quick, cheap print and thin enough it does not affect your shot.

Creality

Ender 3

No

No

.12

Should be a quick single layer print.