Picked these up around last Christmas. These are aluminum repros, but beautiful nonetheless. I have a real Lima builder's plate from a Nickel Plate switcher and anyone would say they look identical in terms of the quality of the casting and the colors.
If interested, here is the website...they make repro builder's plates, number plates and other signs. http://leroyslocomotiveworks.com/ (and they are affordable for most!)
Ask for Jon if you are interested.
Tom