Bucket of sand for a healthy hand!
Walking on sand is a great form of working all the intrinsic muscles of the feet and challenges balance and strength. The irregular sand on beaches is great for this. It is tiring but beneficial for stabilizing the lower leg.
The same can be said for the hand!
Fill up a bucket with sand or even some dry rice. Dunk your hand in the sand bucket, and swirl your fingers and hand around. While your hand is immersed, try opening and closing your fingers, grab some sand, twist your wrist around…virtually any movement in order to tire out the small muscles of the hand that don’t usually get the light of day.
This is a tried and true old-school method of grip training that martial artists, weight lifters and mountain climbers use. It is a great tool to use for either rehabbing finger, wrist, and forearm issues or merely maintaining some grip strengthen for your sport (think tennis, golf, baseball, etc)