I designed this holder for an antenna (wifi) made out of a Pringles can, also called cantenna. It allows to orient and fix the antenna in any direction easily.
The locking mechanism works with a M3 screw, nut and washers.
The mounting joint is a GoPro like double joint (taken from https://www.thingiverse.com/thing:62800 , credits to @MoonCactus), so it will need a M5 screw and nut. As it is a lightweight antenna, you can get by using the plastic screws and nuts made by MoonCactus (you can find them in the same link). Great work BTW.
After that you can attach it to anywhere you want. I personally mounted it to a mirror stand I had laying around after the glass broke. I made a base for it that should work for any smooth rod if you adjust the diameters. You can find it in the download section marked as optional.
PS: If you want to modify or check any of the .scad files, you'll need to download the gopro_mounts_mooncactus.scad file from the previous link, as my files uses the gopro_connector() module.
Happy hacking!