Is the biting about pressure input to your mouth, or pain input to your arms? If it's about pressure input to your mouth, I'd recommend rubber chewy sticks or chewy tubes. You can get them in a variety of shapes and sizes, and in various degrees of firmness from a lot of different places, including amazon. I have a purple grape scented chewy tube that I carry in my purse so I don't chew my shirts or pens, and I find the grape smell relaxing.
If the biting is about pain input to your arms, is there some other kind of sensory feedback you could replace it with, like pressure from a weighted blanket, or high impact force from crashing into things like sofa pillows or foam mats?
I bite my fingers when I'm in the middle of a meltdown; I've never drawn blood, but both my index fingers have callouses on them. I've been trying to redirect my energy from self-harming to other things like scribbling in colouring books and shredding paper, and it works for the most part.
_________________
"Survival is insufficient" - Seven of Nine
Diagnosed with ASD level 1 on the 10th of April, 2014
Rediagnosed with ASD level 2 on the 4th of May, 2019
Thanks to Olympiadis for my fantastic avatar!