Could work. I would be concerned though that it might come off somewhere. Another idea. Fill an old coffee can with the stuff, Or, the Gatorade bottle could work also. Give it to a couple kids and have them roll it back and forth on a table all afternoon.
I recently bought a ball at REI that you put ice and rock salt in one end and cream mixture in the other. Roll it back and forth and around for about 20 minutes and you have Ice Cream. After the first time I used it, I thought it might be a good form of therapy or exercise for your hands, arms etc. My dad has Parkinsons and has trouble with arthritis and other pain with his arms and shoulders. Due to the Parkinsons he needs to keep up his arm and upper body strength to make up for his problems moving his feet and walking. And to prevent atrophy from lack of use of muscles etc. The weight of the ball, loaded up, seemed fairly significant. I could feel the effects of rolling it around for a while and thought that it might be beneficial for someone like him while he was just sitting in his chair watching TV, to be rolling this thing around in his hands. And, you get something in return in the end.
I was watching, I think it was Mr. Wizard one night and saw a similar thing with a small coffee can, (cream mixture) inside a large can, (Salt and Ice) tape the ends and roll them around and it does the same thing. Basic ideas between this and the ball would seem similar to that of a tumbler. Just using one canister rather than one inside another. Load it up with your medium and some coins and tape it shout or close the bottle.
Actually, regarding the tumbler thing. They don't roll that fast. Some go round and round and others go back and forth. So, sitting at the table or while going for a walk, or just watching TV... and turning a jar full of stuff would seem very possible and might be a similar good form of exercise. See if that works.
