Here is my 2nd attempt at a belt clip for my Anker Powercore+ 26800mah battery when I use it with my HTC Vive Pro Wireless Adapter. This time the clip holds the battery all by itself, no more velcro.
I reused the belt clip portion from my 1st Belt Clip and I designed a half height sleeve and a separate arm to hold the battery in place. This design choice was my attempt to minimize the print height and amount of plastic used. The clip is oriented so the battery hangs horizontally, which makes it pretty stable considering the size of the battery.
After printing the arm you will need to use a knife to cut two of the corners down a bit so it will fit into its slot. I left the bottom of the arm flat in hopes of preventing the print from curling. The two cuts are very easy and the arm fits in the slot very firmly without the use of glue. Though I may still glue it in the future.