Therapy is a great tool for giving hand and wrist muscles a good workout. We had it out the other day. It can be hard work to get it soft so you can pull it. That is all part of the workout.
One of our favourite things to do is to hide little things in the theraputty. I have some little plastic things that I bought at a thrift store once -- whale, starfish, lobster, and other things.
I hide them and then she has to work the putty to get find the things.
She will pull and twist until she finds them.
If you have not used theraputty it is a fun thing to have for various activities. I will give you a word of caution it does not dry like Play-doh so you do need to avoid getting it in clothing or carpet. It forever stays moist. I know one of our theraputties is at over five years old and it is still as good as when it was given to us.