a makeshift charger for charging individual 26650 cells (any length technically works but this is what i had it in mind for)

you will need a fitting copper rivet to put into the recess and wire them to the output of a TP4056 lithium charging board (make sure your cell chemistry allows for the 4,2v this will output!)

solder the wireend at the rivet before putting it into the plastic piece!

the idea behind the flanges with holes is that one might thread some wire/string/… through there to hold the two halves together but i found that they friction fit well enough onto the cells to make that not necessary

be aware that by design the ends of the rivets will be exposed and (if in use) will be at battery voltage so treat it as you would treat the cell itself