I don't have an autistic child but have worked with them when I was in the school system with EC classes.
I do miss those special children. You know your child best so If you think this may help, then I would make then.
What about something crocheted or knitted? Any chance he could us that nervous energy to create something like
weaving those old loom potholders? Maybe he could make one then take it apart? Good luck and God Bless you
and him!