Thingiverse https://www.thingiverse.com/thing:5577372
Remixed from https://www.thingiverse.com/thing:4808386. The original model worked, but the corners made it uncomfortable for me to use.
I tightened up the fitment to the mag, added a bolster to the back and flares to the bottom for better ergonomics, and rounded off all the corners to make it more comfortable.
There are a few other small changes like the debossed label.
I included a flat sided version in case anyone prefers that style.
The author hasn't provided the model origin yet.