I’m thinking of how to make the Kadee couplers automatic per car. It’s easy to add them to a locomotive, I’ve allocated two servo controls to my XBee wireless widget controller for that. The tougher part is how to make something that will do individual cars.
Here is what I’ve come up with. It clocks in at about $15 in electronics. Two sub-micro servos for $3, an attiny 1634 at $2 and a WRL-12031 wireless transceiver for $7. That’s $15 per car. Hmm. Still a bit on the high side but if you could have the locomotive be the master and then control each coupler on each car in the consist, you could do some nifty automated switching moves, eh?