Check out www.****.com I bought one last year after my second operation to repair a fractured scaphoid. It sounds silly but works better than advertised. I had my third operation on Feb 10 and will be in a short arm cast for another 13 days. Needless to say, I've been using it daily.
Hello!
I would suggest you to use some body dusting powders to absorb the sweat. Avoid physical activity and if you can limit sweating by staying in a cooler place it is always better for you. There will be some amount of sweating in all individuals.
If you sweat excessively I would suggest you to get yourself examined by your orthopedician and change your cast only if it is very uncomfortable.
Take care!