Place 4 balls in a square with a stump in the middle. Starting in the middle the fielder runs to a corner, picks up and returns the ball to the keeper then runs back to the stumps. Repeat for each ball then rest by putting the balls back. Do three sets.

Variations:

Don't use a ball, instead pad up and run to the marker and back as if you were running two quickly.
Don't have a keeper, simply shy at the stump.

Place three or four balls some distance away from the stumps. The fielder begins facing the stumps. On the call, they turn, sprint, field the ball and return it to the keeper then jog back. Repeat for all the balls then swap with the keeper. Do three sets.

Variations

The fielder/keeper begins in a lying down position.
Use more balls.
Have the ball fed out so it is moving.

Using an agility ladder or mini hurdles, the fielder runs from one end to the other focusing on speed and good running technique. That the end of the ladder the fielder takes a catch fed to them,returns it and runs back down the ladder in the opposite direction. Repeat five times. Do three sets.

Variations:

Try doing backwards running, two footed jumps or sidesteps.
Make the return a shy at the stumps.
Move the feeder to the middle of the ladder instead of the end and complete the catch/return in the middle of the drill.
Add a 10m sprint at the end of the ladder before the catch/return
Add several cones in a curved shape after the ladder to simulate running around the boundary (you can have two ladders and two boundaries to square it off if you like).
Add an extra ladder in line with a feeder in the middle. After completing the first ladder the feeder rolls the ball out away from the ladder the sets off on the second ladder. The first fielder fields the ball and throws it to the feeder who has completed the ladder drill.
Use a heavier ball to catch and return (but counter balance with a tennis ball and normal ball on a 3:2:1 ratio).

1. The coach (wk) starts the game by rolling the ball to position 1
2. The fielder at position 1 completes a 1 handed pickup and underarm throw through the cones to the fielder at position 2. Then runs to position 2.
3. Position 2 picks up the ball 2 handed and throws the ball to the stump at position 3. Then runs to position 3.
4. The fielder at position 3 catches the ball and has a shy at the stumps. Then runs to position 4.
5. The fielder at position 4 backs up the shy and returns the ball to the coach. Then runs to position 1.
6. Repeat as many times as possible.

A fielder starts with the ball in hand. On cue they run to the centre marker, place the ball on the ground and run to the back of the queue on the opposite side. As soon as the ball has been placed, a fielder on the opposite side runs in, picks up the ball and returns it to the other side and runs to the back of the queue. Repeat until everyone has run, placed and thrown.

Variations:

Instead of placing the ball, try rolling it or throwing it.
Instead of returning the ball to the fielder, try shying at the stumps
As pictured, turn it onto a race with two balls and two teams.

Fielder 1 rolls the ball out to the centre; fielder 2 runs in at the same time, picks up and throws it to fielder 4. Fielder 2 then runs behind fielder 4. Fielder 4 then rolls the ball to the centre for fielder 3 to pick up,throw and run to the back of fielder 1. Continue as long as you like.

Variations:

Try shying at the stumps instead of underarm throwing.
Add extra balls.