One server stands on the junction of the 6 yard box and the end line and serves a volley to the goalkeeper. A cone and a ball are placed at the corner of the 6 yard box and the final server stands at the middle of the six yard box. All three stations need plenty of balls

Objective:

The two goalkeepers take turns throwing the ball to each other. The serves can be to the near post or back post.

Progressions:

Both goalkeepers can strike crosses from the ground.
Add some passive attackers to distract the goalkeepers.
Coaching Points:

Catch the ball at the highest possible catching point.
Make the save before the near post if possible.
Decide early, arrive on time