I made this box for a UPS for Huawei's Wi-Fi Mesh routers. Specifically it has been tested with the WS5800 but should work with all routers with the same design.
The UPS fits nicely under the router and has a gap to avoid obstructing the router's cooling.
12V 18650 UPS Board. It is non-specific, so any should work.
I used this one: TZT DC 12V/15V 24W 1A UPS Power Supply Module Uninterruptible Power Control Board 2S V4.0CN Charging Step Up Protection Module - AliExpress 502
18650 Batteries. The board that I used requires 2S, so I used 2 batteries, but any number between 1 and 4 batteries fit.
Model that I used is Samsung INR18650-35E.
Female 5.5x2.1mm DC Barrel Jack.
Male 5.5x2.1mm DC Barrel Jack. I used a right angle one, but a straight one works as well.
6x2mm Rubber Feet. These are not necessary, but help it stay in one place.
2pcs. 3x6mm Countersunk Screws.
The author marked this model as their own original creation.