3D model designed for 5 cell Li-Ion 18650 in combination with powerbank module in link below, the case is made in 3 parts, top cover, bottom cover and button, both covers have special slots for fitting the 5 cells so while moving it it doesn't make sounds, the circuit board is connected to the case using two screws, pattern on 3 sides for rigidity
https://www.aliexpress.com/item/Dual-USB-5V-2-1A-1A-Mobile-Power-Bank-Charger-PCB-Board-Boost-Step-up-Power/32760797930.html?spm=2114.13010708.0.0.3a994c4dcqvXyd