If you've ever used an external power supply for your DSLR or digital camera while mounted to a tripod or other device and noticed the power pack just dangling in the air then you may be interested in the bracket!
The power pack fits snuggly in the bracket and is held in place with Velcro (that you provide). A clamp mounted to the rear allows the bracket to grab the leg of the tripod or any other nearby support, thus removing the strain of having the cord and power pack just dangling in space.
This bracket fits oval power packs marketed by brands such as Bescor, Watson, DigitalFoto, Snnisttek, TKDY, Glorich and others (I think they are all the same, just re-branded by their sellers),
Besides the printed bracket, you will need some Velcro tape, a Small Rig brand "Super Clamp" and a 1/4-20 or 3/8-10 counter-sunk machine screw (about 1/2 to 3/4 inch long).

This is first time I have used FreeCAD to design a part!

I have used AutoCad, Catia, and Fusion360, but all those product have (AFAIK) done-away with their free/trial versions. So I gave FreeCAD V1.0 a try. I went from install to having a finished design for my part in 1 and a 1/2 days. I was quite pleasantly suppressed how easy it was to figure out - I am not an expert, but I can get around and design a basic part as you can see here