Wall

FH Rainbow Rally
If you’re fairly close to the wall, it will force you to hit softer and higher rainbow trajectory balls. This helps you develop a soft feel for the ball, in that you’re not just whacking or slapping or hitting it: you’re racquet is coming from below the ball and brushing or feeling the back of the ball.

Short Wall Quick Prep
On a racquetball court, P (player) rallys against the side wall.
There is not much room.
This ensure that the player hits w/ height and spin to slow the ball.
It also forces P to initiate “C” preparation, immediately after he hits the ball.
You can use the lateral lines near the center of the racquetball court to create boundaries.
This adds further control constraints.