Fidgets/ideas for 5yo that is too rough/handsy waiting in line

We have 3 neurodivergent kids. Our youngest (5M) has inattentive/hyperactive ADHD. He's an amazing kid and has a lot of strengths. Of course standing in line is not easy for most 5 year olds. But the coaches at his tumbling and ninja course classes have informed me that parents are complaining that he is too rough and pushes and shoves kids especially while waiting in line. I have seen this when he is bored, when he is tired, and when he is sensory seeking, but he is being playful and not mean. He is a handsy kid with the whole family at home too. We teach him all the things about keeping hands to himself, about reading other's body language, about listening when people say stop or please don't touch me. And we teach the coaches about sensory -seeking behaviors and how to handle them. But I need to keep our little guy occupied when waiting his turn or he gets too rough.

What are some other interventions, activities, or fidget toys that would be useful to keep his hands busy while he waits his turn? He really only likes cars but those are disruptive and unsafe in the gym area.