SW6106 power bank

I found these neat circuit boards designed for an 18-watt 5v/9v/12v USB-PD power bank, and decided to design a shell to hold one  of them, and two 18650 li-ion cells. 

It has a recessed button to avoid accidental activation in a pocket or backpack, and a friction-fit sleeve/shell that protects the removable 18650 cells while still leaving them easily accessible for replacement/swapping.

Designed for unprotected flat-top cells - protected and/or button-top cells are probably too long to fit.

The indicator LEDs are visible via light-guides (pieces of transparent filament) inserted into the  main body. To make the holes easier to get perfectly positioned and on-size I have included a drill jig. Use a ~1.5-1.6mm diameter drill so that the light guide filament is a snug press-fit, then add a couple drops of superglue from behind and trim them flush to the front surface. Each light guide should be about 6-8mm long.

Bill of materials:

• 1x power bank module: https://www.aliexpress.com/i/2255800990404279.html
• 4x battery contacts, either bought individually: https://www.aliexpress.us/item/3256807497901670.html or harvested from an existing holder: https://www.aliexpress.us/item/3256806641553964.html
• Enameled copper wire for cell interconnects - I used doubled-up 24AWG for each cell contact to keep the voltage drop low.
• Optional: 1/16" thick, ½"-wide adhesive backed neoprene foam to further cushion the cells and make it easier to remove them: https://www.amazon.com/dp/B0DN19B8MR

All printed components are assembled via friction-fit and dovetails, so you may need to scale and/or sand the individual components slightly based on your printer's dimensional capabilities.