Army Painter bottle shaker

My arm was getting tired shaking Army Painter dropper bottles so I decided to make this holder. Then with a mini clamp mounted on a jig saw it makes short work of shaking up paints. Vallejo bottles are just slightly larger and a couple millimeters taller than a standard army painter bottle. Should be easy enough to adjust for them. Also the same design should work for citadel. If anybody is motivated enough to make the other sizes that would be awesome.