I second what Paul said. Shaking hands for aging modelers is a truly frustrating affair, and can turn our hobby into torture. I assume you are already working a with visual magnification device like an illuminated magnifying visor? That can help quite a bit. If shaky hands is a constant issue, aside from tools which hold parts and allow you to steady your hands by resting the palms on them while you work, you may want to speak to a doctor and see if something else can be done. Perhaps you could craft a padded wrist-bench of sorts at the proper height to use while you work on tiny items, such as when you do block stropping. Inventing such a thing might prove useful if you have the bench space for it.