I've got a pvc pipe extension which I fit to one of my pointers sometimes for water hunting and it has a magnet attached to other end.
It may work ok for that style of hunting it's only about 400 -500mm long from memory.
Quite amazing how many eyeball finds he spied apon as well, good on him for thinking out side the square..........oh and giving us something to think about.
HH Iggy