Mike - you are way out of my league. I only know lost wax, and even then only enough to get somebody else to do the investment and pour metal. Cutting Bob's perfect casting was not even discussed - we agreed I would return it intact. It would kill me to cut it, then find out that the entire process would be too expensive to be viable. I have not yet packed it for shipment - I will wait until next week.
No word on the cost of the complete Wolfer truck cost. I don't want to become a pest. Bob Stevenson is ready to make molds and cast the first set of the Lionel part. We have not finished our discussion on two piece vs. four piece. He is the expert, but I foresee problems with the two piece approach.
But hey - if the state of the art is such that a 3D printer can duplicate this casting in wax, that is a non-destructive approach, and we can surely cast that in one piece in brass or bronze, with very little shrinkage. If Mike can stick a good casting in the bowels of such a printer and deliver a wax or plastic copy for, say, $50 each, we are still in the ballpark.
If you can get someone to make a 3D scan of your good truck, then there's no reason why you cant get it 3D printed.
I have bought brass parts from the Ways of Shape. They print it in wax then cast it in brass. The natural finish is quite good, without any printing lines/waves.
The big step is going to be getting the high quality scan of the part into a computer.