Set up a line of 3 balls 10 metres apart. Place a cone 10m from the first and last balls.
Player A starts on the first cone and runs and picks up the first ball with 2 hands, assume the "set throw" position, and throws to player B on the other cone.
Player B retreats 10m and puts the ball down.
Repeat with the other 2 balls as above. Then your partner will throw back to you.
Repeat the process.
Check the "set to throw" position is side ways on to the target with the ball behind your head.
Step through the line of the throw moving towards the next ball.
Distances should be adjusted to suit players ability.