This is a battery tube to fit a NiteFox e1 flashlight, allowing it to use a single 10180 battery instead of its normal three LR44 coin cells. More flashlight detail at the end.

There are three variants of the battery tube- one with a lanyard hole centered on the tail, one with it offset, and one with no lanyard hole for the shortest possible configuration. Update: I added a fourth with the lanyard hole in a tab on the side of the body.

In addition to one of these battery tubes and a 10180 battery, you will also need to put a strip of copper tape running inside the battery tube from the bump at the bottom, up to the top edge and even over the threads. The O-ring on the LR44 battery tube can also be put on the new battery tube, but you may need to seal the print to achieve best water resistance.

The parts should be printed tail down, not on their sides like in the STL models. I printed the pictured battery tubes at 0.2mm layer thickness to get adequately formed threads, and 0.4mm line width for two layers at the thinnest part- the groove for the O-ring. Due to shrinkage, especially with the walls being only a few layers deep, you may need to either scale the part bigger in X and Y, or go into the Fusion 360 part file and increase the dimensions. The thread outside diameter should measure to about 13.3mm. For my parts on my poorly calibrated printer, I changed the user parameter KludgeOversize from 0 to 0.5mm.

The model file has all three variations of the part, just roll the history marker back to the corresponding grouped features. Update: Now all four variations, and I've added a parameter for oversizing the threads because they're pretty small at just two or three layers thick.