I've had this small Eddie Bauer/Coast flashlight for awhile and because it doesn't have any texturing/knurling on the head or body, it wasn't easy to twist on/off one-handed. Adding a Turk's head knot helps.
I extended one of the bights of this 'long 3 bight turks head', made with 1.4mm nylon cord, for use as a wrist lanyard. I added the Solomon bar/Portuguese sinnet over that single strand.
There's almost 12 feet of cord used in the TH knot and close to another 10 feet for the wrist lanyard.