Robin,
You may not have to post it to me at all. Here's a bit of information on them. I personally haven't ordered any castings yet. But I know others who have including my father. And the process was just as described in the link here. Mail them the pattern with the type of metal and quantity desired and a while later get the pattern and castings back along with an invoice.
http://wiki.vintagemachinery.org/FoundrySources.ashx
Matt