I am a subscriber to Gormo's You Tube channel 'Great Chesterford Junction Model Railway'. He invented a highly innovative method of 3 link coupling operation for 00 gauge rolling stock based on magnetics. I thought about adopting it for my 0 gauge rolling stock but came up with a simpler method that was implemented in seconds without the need to modify stock and gave remarkable results. I doubt it is suitable for smaller scales though.
I had available a range of neodymium magnets and found that a 4mm diameter by 1 mm thick magnet fitted snugly into a loop of a 3 link chain. Now, for this to work your chain needs to be ferrous metal.
With two wagons modified I brought them together by hand and they joined up instantly. pull them apart and they decoupled. What a delight, as anyone who uses a shunting pole will appreciate!
There was a tendency for the magnet of one chain to release from the link to snap to the magnet in the other chain. This was easily fixed by super-gluing the magnets in place. You would think that the distance between wagons would double normality as the chains do not couple to the hook. However, what happened was the links concertinaed due to the magnetic force, thus restoring the prototypical gap. Of course that effect on the chains is not prototypical but it is a small price to pay for ease of coupling up the rolling stock.
This method has potential for further development. Maybe soldering the three links together for rigidity or having two links non-ferrous and the magnetic link ferrous or indeed all links non ferrous. Something else to bear in mind is the chassis. If this is ferrous or parts there on near the links are then this will attract the local magnet in preference to coupling up.
