Ghost ball trick: It's the exact size as the object ball and always frozen to it. You can train your eyes by freezing the CB to another ball and walking around it till you memorize the look or you can no longer miss.
Also this might work:
A right triangle half the height of the object ball.
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Here's an interesting artifact of Jimmy Reid's Equal Angle Opposites:
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The Yellow line shows the intended object ball line.
The Red line is contact line. You can use your stick on close shots to get the hang of it.
The Black line is the shot line running parallel to the Red contact line.
Notice, the Black shot line intersects the Yellow shot line at the base of the mythical Ghost Ball.
The blue line is just the line of centers.
The half ball hit is incidental. Could be any pool shot angle; different angles and parallelogram but the connection points would be the same.