@Dio9sys Basically, attach a pull string, drop into conduit, crawl space, or drop ceiling. Go to the other end and squeak a toy they have been trained to come to. Reward with treats!
I would NEVER drop a ferret into ductwork, I've had some get in on their own and it sucks to clean them afterward. Nor do I recomend using ductwork to run cabling, unless you are pulling rated cable through a a plenum.
@Dio9sys I do not recommend this technique unless you are an exprienced ferret handler.
They can be.... unpredictable chaos tubes.
@nuintari @Dio9sys My favourite way to give my carpet snake a workout was to bring out the plastic dryer-duct, then kneel down on the floor and run it around me... It didn't take much encouragement to get him into the tube, then, once he was about half way through, I'd put the two ends together, and let him run 10 or 15 times. :)
He would have been a great assistant for running cables in conduits. :)