My Occupational Therapist writes:
Exercise putty (Or "Theraputty") is commonly used to strengthen muscles within the hand. ... PlayDough is not the same as exercise putty so I'd recommend ordering some from online. Here's a link to exercise putty online through Amazon. There are four colors, each with a different level of firmness:
FlintRehab Premium Quality Therapy Putty (4 Pack, 3-oz Each) for Hand Exercise rehabilitation:
amazon.com/Premium-Quality-...?
Amazon keyword: therapy hand putty
In terms of exercises, Saebo.com has a great blog with a wide variety of topics including best hand exercises. They cater to post-stroke population but these exercises can certainly be used for anyone wishing to improve strength within their hands. The first six exercises have a therapeutic ball but all of those can be used with putty. The remaining exercises use putty.
saebo.com/reclaim-your-dext...
For dexterity/fine motor coordination, here's a list of good exercises/activities:
PRACTICE THE ACTIVITIES MARKED FOR 30 MINUTES TOTAL PER DAY USING WEAK HAND (unless otherwise noted):
( ) Pick up one coin w/ each hand & drop into a container at the same time.
( ) Hold a deck of cards in R L hand & sort into suits with R L hand.
( ) Play scales on piano/keyboard using R L Both hands.
( ) Typing drills on computer/typewriter using R L Both hands.
( ) Use a calculator.
( ) Thread buttons or washers onto a shoelace/string/twist tie using R L hand.
( ) Dominos, Yahtzee, dice, Cribbage, Solitaire, Concentration card game, shuffle cards.
( ) Print/write/type: The sly lazy dog jumped over the quick brown fox.
( ) Punch golf tees into the flat surface of a cereal/tissue box then move them around the box using/ R L hand.
( ) Pick up small ¼” ½” 1” diameter objects, store in your palm & then push them out of your hand by using your thumb.
( ) Roll golf ball down R L palm & out through fingers.
( ) Hold two balls in R L palm, then exchange places of balls without using other hand.
( ) Put coins, 1” 2” diameter item in pocket with R L hand & remove it.
( ) Tie fishing lures.
( ) Large patterned & needle cross-stitch, crochet or knitting.
( ) Sort small nuts, bolts, screws, nails.
( ) Make jewelry with 1/8” ¼ ½” 1” beads.
( ) Jig-saw puzzles.
( ) Drawing or Doodle art.
( ) Flip/Turn pages of a book/magazine using R L hand.
( ) Screw nuts onto bolts (progressively smaller)
( ) Origami or folding letter sized paper or cardstock & put into envelopes.
( ) Put away silverware.
( ) Use a ratchet-type screwdriver.
( ) Open & close plastic storage containers, medicine bottles.
( ) Tie shoelaces @ lap level or tie a long twist tie in a bow.
( ) Button shirts @ lap or table top level (progressively smaller buttons.)