Starting with the hand held out palm down at chest height one exercise was to rotate one hand 90 degrees in the vertical plane so the thumb is down (lower) and the little finger is up (higher). The palm is perpendicular to the floor and the fingertips are parallel to the floor. At the same time the other hand rotates in parallel so the thumb is up higher) and the little finger is down (lower) with the palm perpendicular to the floor and the fingertips parallel to the floor. This leaves you with both palms facing the same way. Let’s say you rotated the hand clockwise so the left palm faces out and right palm faces in. The hands move inward toward your centerline and the right palm contacts the top of the left hand. The right thumb crooks over the abductor muscles (“knife edge”) of the left hand. The right index finger doesn’t really do much. The other three fingers of the right hand hook around the left index finger. Now you gently rotate the hands about 30 degrees vertically upward. There should be some tension on the distal knuckles of the left hand (for little and ring fingers) and near the pisiform bone in the wrist. Then you slowly bring the the wrists to touch your breastbone. Repeat for the other wrist.
a short video: https://www.youtube.com/watch?v=7bTMzjPq4qY