I have for many years been looking for a manual uncoupler for Kadees that works. I bought the Kadee version but it hardly works at all except it is better with the new scale head couplers. Another, the Rix Products version uses two magnets that are placed between the wagons either side of the couplers, unfortunately, since I am modelling NSWGR in 1965 many wagons have buffers so this uncoupler can't be used.
My first attempt at making one many years ago (20+) worked well but it was always difficult to see between the wagons.
While doing the grocery shopping a week ago I noticed a clip on LED book light and the penny dropped and here is the result.
This uncoupler really works very well, the video shows the uncoupling of various types of KD and KD clones in various combinations, The only slightly issue is with the plastic KD clones as the uncoupler occasionally catches slightly but as I intend to replace these it won't be an issue.
Incidently, the new scale head whisker variety of KDs are very good, much better than the old standard KD No.5.