Buckling Rings before placing on pole

I have been using a ring stack activity with a tall pole and soft fabric rings made out of socks for years. Placing the rings develops bilateral coordination, postural control and balance when young children work in kneeling, standing positions and reach out of their base of support. I can add challenge (a lot of challenge) by asking children to buckle the rings before placing them on the ring stack. I cut this ring out of a large plastic bottle and  cut notches so that the ends can be buckled together.