I'm inclined to have have one made, the problem is they are just a little larger than a standard nickel.
There is also a 1996 mule Hobo/locomotive, of course I have one. It was easier to find that the boxcar.
I'm sure Capital Plastics could make one for you. You'd just have to give them the coin diameters. Check them online.
I've used them before on a couple items. This time I may use one of these, plus they don't cost as much Floating frame MAGIC FRAME 230 I used something similar for my 2 oz. Peace Token