Setup. Three flat markers in a zigzag, two metres apart, in front of goal. Server 8 metres beyond the last marker.
How it runs. The keeper bounds from marker to marker, one leg to the other, sticking each landing for a second. Off the last marker they take one step and jump to catch a ball the server has thrown high. Walk back. Six reps, starting on a different leg each time.
Make it harder. No pause on the landings. Then the server delivers to either side, so the last bound changes direction.
With 4 keepers. Two stations: a worker and a server at each.