Not sure of the link right off hand but I believe there's a German outfit that has some made out of pot metal or brass....but they are pretty pricey for as fragile as they appear.
Maybe try some spade connectors that are used for wiring and give that a shot...
I've been meaning to try this on a truck....only problem is apparently you have to have a completed truck for that to work, LOL.
Best part is you can get them in blue, red, and green so therefore you can replicate service and emergency air, as well as your electrical.
I think they would look the part, and be strong enough to stay together when making turns with a truck and trailer.
-Alex