Intetesting discussion. One of my friends is building a HO and HOm layout, so 16.5mm and 12mm gauges with ‘european’ couplings. We’ve been struggling to find a way of making uncouplers when this thread popped up. Latest suggestion was square brass tube through the baseboard, slightly smaller square brass tube through it, uncoupling plate (brass, plastic or 3D printed) on top, servo under the baseboard to push the ramp up. But we’ve no kniwledge nor experience of using servos. Happy to be DC or DCC operated.