This is a paracord DIY(Do It Yourself) version of a Maglite C/D cell type flashlight holder using the cobra stitch/Solomon bar/Portuguese sinnet knot. I made this one a bit larger than the belt it's on, but you can make your own sized for whatever belt you might intend to use it on.
This one is made where it can be put on or removed from a belt without having to take the belt off. You could also make the loop static by tying a stopper knot(over hand/figure eight etc...) where it can't be pulled thru the knot and has to be slid on/off the belt.
And here it is with an overhand(stopper)knot tied at the base of the loop, so the holder has to slide on/off the belt when finished like this.
An alternate method for the loop could be to attach a rubber o-ring that's large enough to fit the flashlight body and not the flashlight head.