In reviewing pictures for this post, I ran across the picture below. A child is filling the jug through the hole. That was expected. What was not expected was the other child watching the operation through the small cap hole on the end.
Sometimes it just takes a willingness to play with objects---almost like a child---to see a idea become a reality. By the way, I joked with the parents that this component originating from adult world of washing clothes allows the children to work on the "life skill" of pushing the button of a laundry detergent jug.