If you want to experiment with weighted vests, you can start with a decently-proportioned child's backpack filled with soft/cushioned items totaling various weights. You can also try fidget toys (stress balls, koosh balls, etc.), or one of those rubber bracelets with an inspirational phrase on it, or a theraband looped around the legs of his chair (for hooking feet through it, or bouncing).

...pronounced like the long vowel and first letter of the alphabet...