Great idea! Why is it that magnets are just as fascinating today as they were when I was 5?
I played with them recently and created a magnetic tether between loco and tender that ties all roller pickups together. Probably not the safest of electrical circuits but the smooth operation over switches and quick connection outweighs the consequences. Crude as it is, some improvement in soldering and well placed, colored shrink tube could duplicate the connectors you've created, without the need for a 3D printer.
A LionMaster Pennsy T1 that embarrassed itself on every #5 switch became a docile and obedient giant with the engine to tender electrical connection.
BTW, when you solder a wire to a small magnet there is almost a total loss of magnetism. I simply added another live magnet to the dead one and covered both with shrink tube, flush with the magnet end. Note the tender connector isn't as neat as the engine connector....a case of improved assembly skill in relatively little time.
Bruce