I made mine but Hart Fab on here makes something similar:
https://hart-fab.com/collections/fro...ination-pocket
Here is what I got off Amazon:
https://www.amazon.com/Fastronix-Pre...NsaWNrPXRydWU=
Or you can get it premade (though I am sure you can make it yourself):
https://www.amazon.com/Battery-Charg...s%2C253&sr=8-4