Hand Strengthening Activities?

I've been in this field for quite some time so the basics...such as playdough...is being used. But I was wondering if there are tried and true hand strengthening activities you'd wish to share? I have a little guy in my program who does not care to write or work with small objects and truly I think it's because his hands tire out quickly. His grasp on scissors and any type of writing tool or toy is not firm at all and his confidence level is down because when he does try to use a writing tool the results don't meet his *expectations*. So any "new" ideas of how to strengthen those muscles in the hands? Thanks!!!