This is a design i have not test printed it the measurements are as close as possible with out having a 26650 to match it, the 18650 is pretty dead on! theres also little dimples in the side so u can print a pin and connect them together for dual battery config. u can add + - signs to the print as needed Needed: 20, 18 or 16gauge solid copper wire or any wire you can make a spring or pin for contacts use a 10 to 15% fill when printing it will still need to flex to remove battery from holder if you print on a heaver fill battery might get stuck in place! I suggest you check measurements in google skp before printing enjoy! -ChungPow Mike