Doubled Spanish Ring Knot
A discontinued keychain LED lantern flashlight that I've had for several years, kept in the gadget drawer.
Took it out to use a leftover scrap strand of red 0.9mm cord and tie a doubled Spanish ring knot around the groove of the light body.
www.riverrockledlights.com/shop/micro_lights/nightfire_le...
Target used to carry a variety of the River Rock LED lights back around 2006 - 2009, and I'd bought several different models when they went on clearance.
Similar models might still be out there on the interwebs.