There is a plastic one available on Etsy, but I haven't tried it.

For my Armbars, I just use a suspension clip like one of these:

https://www.amazon.com/gp/product/B07KPKW72Y/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

or

https://www.amazon.com/gp/product/B07KPLGBDH/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1