Recommend a universal holster for a 18650

Glad you like it. If you are carrying small lights in it make sure to put a zip tie or something underneath it so the light doesn't fall out. I learned that the hard way when I lost my Surefire G2X. (Found it 2 years later yet it still worked) :)

Here is several models of rotating holsters, the last one of the first message is said to be “universal” (adjustable + additional options):
http://loupiotesaddict.pro-forums.fr/t898-holsters-etuis-pour-porter-transporter-nos-precieux#10609 (in French but with pictures to illustrate)

A presentation video (in German):

The manufacturer’s website: