My son flaps his arms, makes a noise like a moan, spins in circles, sometimes claps. I can honestly say iv never noticed a child stimming, the only time I remember is at a zoo a child having a wee melt down, obviously struggling, and a lady giving the mum looks and making comments, to which I made comments back to the rude lady
my son was a baby then so had no experience of autism yet but it was very obvious he was struggling and overwhelmed. Probably something Vav would have done pre M (the rude one)