Extra large Stringing Adaptation with Tubing

Someone at work donated some blue tubing used for suction. I immediately thought of making an adapted stringing activity with marbles or beads inside that they can shake. You can see them moving around inside and individuals who can't string can use this more like a rattle or try to motor plan to make the beads travel from one end to the other.

I am still experimenting with designs.  The one in the video shows a tube attached inside a box. I thought that this would be a nice way to have a container ready to hold the rings before stringing. However, some people prefer to hold the tube with the bottom dangling on their lap. I am exploring lengths that will promote reaching but not frustrate too much when pushing the rings down. 
You can see that the woman in the video needs to grasp the tube closer to the attaching end and doesn't know how to untangle the twist in the tube. So I like these motor planning challenges in what appears to be a relatively simple task.

I am thinking about making  rings to stack by inserting the marbles inside and closing the ends to make small rings that they can shake before stacking. If you swirl a long piece of tubing it makes a cook sound. .....What other ideas do you have for  making tasks out of the tubing?