Pictured is a tooling resin 1/12 scale PC&F R-40-23 Refrigerator car Dreadnaught end. This is a classic example of an old-school method of tool making. An individual rib is carefully shaped and upon completion a 2nd generation part is mated with 5 others and skillfully joined together to make the 1st generation tooling resin reefer end.
A time intensive large scale model of the end is used as a tracing pattern for cutting a hard tool aluminum mold using a Deckel 3-D pantograph.
The pantograph allows several different scales as recipients for this large scale design. 5.33:1 reduction gives you an S scale part, and a 7.25:1 reduction yields an HO part. The parent large pattern is pictured below.
I have also included a picture of a pair of R-40-23 HO ends. The NP numbered part is from an Intermountain R-40-23 kit, and the grey resin part is a next generation part from the parent large scale pattern. The IM part is from a mold made with CNC tool cutting technology, and the resin HO part is from the old-school method.