This is a simple exercise that I learnt during the physiotherapy class in which we attempted visualisation.
Make you hands into fists – as tight as you can.
Then release the fists and stretch out the fingers to make a star shape – as wide as possible.
A few repetitions should release some of the tension that has built up in the hands and forearms (my left hand gets very tight at times; it’s uncomfortable, verging on painful) and may also restore some of the ‘lost’ function for a short time.
I find it slightly easier to do this exercise with both hands simultaneously; the able right hand ‘leads’ the left. It certainly loosens the affected hand up, and it does seem to help with functionality. I hardly lost any ‘A’s on that last bit of typing!
Incidentally, even with a half-frozen left hand, the darn thing doesn’t stay properly still to be drawn! I had to reposition it (a trivial task) several times for each drawing.