Tripod for smartphone
This is one of my favourite bits of kit, but it never gets seen! It is key to one of the most valuable training tools you can ever have - the ability to film your training sessions and watch them back.
The legs will ensure your phone/camera remains steady whether it's attached to a fence, a jump stand, sitting on top of a barrel, wrapped around a tree branch, or anywhere else you can think of. I often attach it to the top of a road cone at one end of my arena.
Videoing your training sessions is one of the most effective ways to improve. Become a better trainer, all from the comfort of your own home and without needing help from anyone else.
They're pretty robust - mine is still going strong after several years, even after being chewed by my delinquent pony.