My clients seems to really enjoy this ring stack. I happened to have a cardboard tube, some plastic dowels and these rectangular shaped plastic containers. So I wedged 2 dowels into the tube and then attached the rectangular container.
I knew that they would have to stabilize this because it rocks around otherwise. But they seemed to like the cognitive challenge of matching the small round shapes to the dowel and rectangular shapes to the rectangular stack. They realized quickly that the smaller round shapes won't fit over the rectangular stack and understood where the larger green rectangular shapes needed to go. In addition, the lady with the striped sweater avoids using her left hand so this activity worked on her goal to stabilize with it.
This activity works on many skills that are appropriate for individuals with developmental disabilities.