DIY Dummy 18650 Magnetic Battery Charger Adapter - A solution to charging 26800's and other large cells without having to buy a new charger (details inside) : r/flashlight
18650 to 20700/21700 Battery Adapter by AnalogDan - Thingiverse
18650 Battery Adapter for 2 C-Cells by cohocarl - Thingiverse
LiIon 18650 to 26650 adapter by viktori | Download free STL model | Printables.com
Flashlight adapter 3xAAA to 18650 & 18500 by Marin | Download free STL model | Printables.com