EMT conduit hangers work great. Here is a photo of one holding a Maglite flashlight.

I glue bits of old inner tube rubber to the inner surfaces to protect the flashlight from scratches.
Conduit hangers are sold in hardware and building supply stores in the electrical supply area and cost less than a dollar for the small ones. While your purchasing your conduit hangers buy a 1/4-20 thumb screw so no tools are required to loosen the hanger allowing easy removal of the flashlight.