My clients get bored with doing the same activities, so I try to make small variations to keep their interest. This ring stack has a couple of balls attached to the top. I can shake the pole to draw their attention to the top of the pole where the ring needs to go down. I cut the openings in the plastic to be small enough to require a bit of motor planning to make the balls fit through. I found that this worked well with some individuals while seated and others while standing at the table promoting reaching at eye level. 
