For those looking for custom foundry work in Iron, Aluminum or Bronze I would recommend the Cattail Foundry located in Pennsylvania, USA. I have used them for many years in the support of 1.5 2.5 inch live steam locomotives castings. It is owned and operated by Mr. Benjamin King and his son Emanuel. They do one off parts as well as large orders on everything from full sized steam tractors to the smallest of items. They have supported the live steam hobby here in the United States since the 1970's and their integrity is exemplary.
They are located at:
167 W Cattail Rd
Gordonville, PA 17529(50)
I should mention here that they are an Amish family and while they do have a phone, you will have to call and leave a message to which they will call you back to discuss an order.
The phone number to reach them is: (717) 768-7323
As my parts are small for 2.5 inch scale locomotives I usually have my parts shipped which they are able to handle.