What I was requesting was photos of the tool(s) used to create plastic kits as I have never seen one.
Bill Welch

Not railroad molds, but I think some of them might be like this
http://image.made-in-china.com/2f0j00pvFECRnDOQru/Plastic-Molds-Injection-Plastic-Molds-Plastic-Mold.jpg

Interesting info and pictures here
http://en.wikipedia.org/wiki/Injection_molding

The Branchline mold I saw had lots of holes on the smooth backside,
for the ejector pins and fluid injection.

Tim O'Connor