Remixed cap from https://www.thingiverse.com/thing:4957973 for Olight M2R Pro Warrior to prevent accidental backpack ignition.

Instructions (VERY IMPORTANT):
1) On your slicer tool (e.g. UltiMaker Cura) uncheck "uniform scale" and resize this STL file to 29.2mm (axis X and Y) and Z to any value from 18mm to 22mm. Tested with Ender 3 w/ PLA, you might have to play a little with these numbers, and you can offset Z to bellow surface to save a few layers.
2) After printing, to improve tight fit and strength, anneal it in the oven (bake) at 100C for between 45s to 75s, until its softer but not too much soft.
3) Squeeze it in the Olight while it is still hot and wait for it to cool down.