Rolling stock for Steel Mill Module in N scale

My neighbor and I are well along on the construction of a Steel Mill Module for his garage layout.

We started with the Walther Blast Furnace and Rolling Mill kits and scratch built all the other necessary structures.

Now that the the bench work and general layout of the module is complete, we have only one major problem remaining. Where can we find Slag cars and Hot Metal cars in N scale. Walthers makes reference to Minitrix in the instructions for the Blast Furnace, but no information appears that we can find.

If anyone has any information regarding this equipment, your help would be GREATLY appreciated.

I’m sure you can understand our level of frustration at not being able to populate the module with the correct equipment.